Deoxidized High Phosphorus (DHP) Copper tubes are frequently used in numerous industrial and household applications. To ensure the acceptability of DHP copper tubes prepared by various industrial processes, the quality of the DHP copper tubes must be evaluated. Drift expanding test is one of the best ways to do so is to examine the quality of tubes. In this paper the authors considered the mechanical properties of various DHP copper tubes manufacturing processes using drift expanding test. This paper concludes that there is a large difference in the mechanical properties of tubes with different manufacturing methods. Planetary rolling have a better expanding percentage than cast or extruded tube samples.
During the last decades there is continuous tendency to lower the weight of cars and thus automotive industry is trying to find other metal (or e.g. plastic) materials suitable to produce lighter car-bodies. As one of these materials can be taken also magnesium alloy AZ31B-0 that is suitable for forming. Among advantages of magnesium belong mainly low specific weight, availability and relatively inexhaustibility of its sources. As a disadvantage there is mostly low Young´s modulus and crystallization in the hexagonal-closed-packed lattice which causes limited ductility of the magnesium at room temperature. Metal forming technologies for the magnesium alloys respect this specification about hexagonal-closed-packed lattice of the basic solid solution and its microstructure. Low ductility at the temperature of 200°C is caused by the low number of the slip system which takes place only on the basal planes. Under temperatures over 225°C are already acting more slip planes. The paper deals mainly with the results of the experiment where was by the contact-less optical system ARAMIS determined strain distribution and its maximal magnitudes in the fracture vicinity under the uni-axial loading at different temperatures. Eventually new grains creation and development of the recrystallization was examined by the optical metallography.
A surface layer enriched with Zn was formed on Mg by heating the specimen painted with a ZnCl2+KCl containing paste at 440 oC for 120 min using no protective atmosphere. The study focused on the microstructure, phase constitution and microhardness of the alloyed layer. The layer, which was about 200 µm in thickness, had a eutectoid structure (an MgZn intermetallic phase + a solid solution of Zn in Mg) with some dendrites of a solid solution of Zn in Mg distributed over the eutectoid matrix. At the interface between the alloyed layer and the Mg substrate, there was a zone of a solid solution of Zn in Mg. The thermochemical process increased the hardness of the specimens at the surface from 30 HV0.1 (Mg) to 110-164 HV0.1 (the layer containing the MgZn intermetallic phase).
Metallic foams are very perspective candidates for light-weight structural applications in automotive, aerospace, naval and construction industry. However their mechanical properties are very sensitive and different density regions and structural anisotropy can significantly affect the resulting mechanical properties of products. In this study the compressive properties of samples excised out from different parts of relatively large block of Al foam Alporas have been measured. The effect of structural parameters, density and strain rate sensitivity were discussed.
Hydrogen solved in amorphous alloys (AAs) influences their magnetic characteristics. AAs are also perspective as additives that can improve hydrogen storage kinetic in certain types of ball-milled hydrogen storage materials (HSMs). Therefore, knowledge of hydrogen solubility and hydrogen sorption kinetics in AAs are of a great importance for aimed design both AAs with optimal magnetic parameters and HSMs with desired sorption characteristics. In the present paper, amorphous alloy Co30Fe55B15 (an example of the type a-TM1xTM2yBz; TM – transition metal) was investigated. Hydrogen concentration cH was measured by Sieverts method in temperature interval from T = 150°C to T = 350 °C under hydrogen pressure p up to 60 bar. It was found that cH was an increasing function of T and p and its maximum value was typically 0.5 wt. % H2 at 350 °C and 60 bar. However, when the alloy was preliminary hydrogen charged (PHC), the pressure dependence of total cHtot in the first sorption cycle(s) is non-monotonous in dependence on PHC conditions. For the sake of comparison, the same sorption characteristics were measured also in Mg2Ni intermetallic that is a common constituent in Mg-based HSMs. Comparing Co30Fe55B15 and Mg2Ni, it was concluded that Co30Fe55B15 shows lower hydrogen solubility, but much better sorption kinetics.
CoCr alloys are used for production of dental prostheses using casting or newly by Selective Laser Melting (SLM). EOS Cobalt Chrome SP2 is a Co, Cr, Mo and W based alloy in fine powder form. Its composition corresponds to type 4 CoCr dental materials in EN ISO 22674:2006 standard. It also fulfils the chemical and thermal requirements of EN ISO 9693 for CoCr PFM (porcelain fused metal). In our paper the size of initial powders, chemical composition of CoCr – based alloys, microstructure after SLM and heat treatment, X-ray EDX analysis will be studied. The main problem is the porosity of material and stability of the shape of prostheses after high temperature annealing.
The spent auto catalytic converters are a valuable source of platinum group metals, such as platinum, palladium and rhodium. There are two main types of structures used in catalytic converters – with ceramic or metallic carrier. Metal supported auto catalysts, have been used in sports and racing cars initially, but nowadays their application systematically increases.
World literature describes a number of pyro- or hydrometallurgical methods used for recovery of platinum from used automobile catalytic converters. However, all the methods, available in the literature, are used to recover platinum from ceramic carrier. Among automotive catalysts withdrawn from use, these with metallic carrier constitute quite a big group.
This work presents a method of PGM metals recovery from auto catalytic converters in which they are wash out by a liquid metal. Liquid metal is put in motion by means of magneto-hydro-dynamic pump, and then the PGM metals are eluted from channels of the used auto catalytic converters. Analysis of platinum contents in the carrier before and after the process was performed using atomic absorption spectroscopy. The obtained results were discussed.
The increase in the production of packaging, among which are a large group the waste steel cans containing tin, requires exploration and implementation of new methods for the recovery of packaging waste which constitute a large share in the municipal solid waste stream. In order to determine presuppositions newly designed methods for recovery of tin from waste steel cans, it becomes necessary to determine the basic parameters of chemical processes, which can be an essential or additional element of effectively working installation. Described in this paper the results of research concern the basic parameters of the leaching process tin steel sheet metal cans of waste - as input data necessary to determine the scope and process of its recovery. The research material were samples of steel sheets used in the production of cans for food products, coated with tin and one or both sides covered with a layer of varnish. Samples were subjected to preliminary mechanical treatment in a roll mill, and then leached in 1 M NaOH solution. The essence of the study was to investigate the possibility of removing the tin from sheet steel waste, which can be use in the metallurgical process - as a source of iron. At the same time depleting the world's natural resources of tin classifying it into the group of critical metals requires to search the methods of recovery tin from raw waste materials. The research results presented indicate the need for further actions related to the establishment of standard technological requirements necessary to design and supervision of the process recovery tin from waste steel sheets.
High-entropy AlCoCrFeMoxNi (x=0.5-1.0) alloys were prepared by the vacuum arc melting and casting method. The effects of Mo content on the microstructure, hardness and wear resistance of the high-entropy alloys (HEAs) were investigated. The HEAs were characterized for phase content by X-ray diffractometer (XRD) and morphology by scanning electron microscope (SEM). Wear tests were performed under dry friction conditions with WC balls at a 5 N normal load and sliding speed of 5 cm/s in a ball-on-disc geometry. The worn surfaces of the samples were also examined by SEM and energy dispersive X-ray spectrometry (EDS) to identify the wear mechanism. X-ray diffractometer (XRD) showed that the prepared alloys exhibited FCC, BCC, B2 and σ phases. The hardness of the as-prepared alloys were found to be increase from 710 HV to 747 HV in the range of 0.5≤x≤1.0 with Mo content. On the other hand, the wear resistance of HEAs gradually increases with increasing Mo content. The correlation between composition, microstructure, hardness and wear properties of these alloys is discussed in detail.
The purpose of the present research is to develop the finite element model for temperature field and distortion during friction stir welding (FSW). Experimental FSW of 2 mm sheets was provided for temperature and distortion determination. Aluminium alloy AW 6082 was chosen as a material for workpieces. Temperature was measured by thermocouples. The 3-D geometry of sheets before and after friction stir welding was measured by means of a precise robotic system for distortion determination. An analytical heat source model developed before was improved by taking into account not only the friction at the contact surfaces or close to the contact surfaces under the tool shoulder and at the tool probe sides but also the influence of the plastic deformation in the weld nugget on the heating of the workpieces and asymmetry of the heat source. The temperature distribution and distortion was calculated by means of developed finite element model. The simulation model was compared with experimental results. The results of numerical simulation are in the good agreement with the experimental results.
Study of structural and mechanical properties of metal powders is necessary for improving in powder metallurgy. The procedural behavior of aluminum, copper and iron powders and their alloys is important for many industrial applications. This paper presents how the shape and size of the particles influence compressibility and flow properties of metal powders. These properties play an important role in the storage, handling, dosing and compaction in powder metallurgy processes. For the samples of aluminum, copper, iron and their mixtures has been determined particle size distribution and shape of particles thus posing its mechanical properties. The biggest irregular iron particles exhibit very low compressibility about 2 % at 15 kPa applied normal stress. Conversely the fines copper particles are the most compressible. All of the basic powders indicate low compressibility at low normal load but different mixtures show bigger compression immediately after load application.
Elemental Fe and Cu powders (FexCu100-x for x=10, 30, 50, 70, 90) were cryogenic milled in a high energy attritor mill to extend the mutual solubility of the elemental Fe and Cu. A small amount of Methanol was added as process control agent(PCA) to prevent cold welding at the initial milling while cooling the milling chamber by flowing liguid nitrogen(LN2) around it. The extrapolation fitting of Nelson-Riley function using the XRD data of the milled powder indicated that the solubility of Cu in Fe solvent was extended dramatically as expected. The XRD results also showed that the crystal structure of Fe50Cu50 alloy was a mixture of BCC and FCC at early stage of milling, which later changes to a single FCC as milling proceeded. The exothermic trace of DTA (Differential Thermal Analysis) curve was observed. This is attributed to the negative enthalpy change for the relaxation of the elastic lattice strain energy stored while milling. A preliminary discussion based on thermodynamic consideration to the relation of the extended solubility, Phase transformation, and the negative enthalpy change will be given.
Microstructural and mechanical inhomogeneity of laser (LBW) and friction stir (FSW) welded joints of 4 mm thick 6082-T6 Al-Mg-Si alloy was studied. Measured thermal cycles in heat affected zone (HAZ) showed that LBW has a much higher heating and cooling rates than FSW. Distribution of local microhardness and local strain in tensile specimens revealed that fracture of the joints corresponds to a region with minimum hardness. LBW tensile samples were fractured in weld metal, FSW samples - in HAZ. It had been found that tensile properties and ductility of joints is significantly lower than those of the base metal. The LBW and FSW joint efficiency in terms of yield stress was about 71% and 61% respectively. Joint efficiency in terms of elongation was 7.8% (LBW) and 19% (FSW). It explained by the strain concentration in the lower strength joint region.
The examined materials were created by low-pressure cold spray technique as free standing thick deposits. Used materials for deposition were iron + aluminium, iron + copper and iron + nickel powder mixtures. The working temperature was T = 400 °C and nitrogen was used as the working media with gas flow of 250 slm with pressure about 50 bar. Each deposit was made with different thickness based on the deposition efficiency of the individual mixtures.
Samples were annealed isothermally in argon protective atmosphere. Temperatures of annealing for different deposits were chosen from equilibrium phase diagram for each system. Short-time and long-time annealing was conducted. Short-time annealing was 2 hours and long-time annealing was 10 hours. The resulting microstructure was examined by multiple methods. Microhardness of the phases identified in the reacted materials was measured using Vickers indenter. Fracture behavior and porosity character was documented using SEM which was also used for phase identification using EDS and EBSD measurements. Intermetallic phases and metastable solid solutions with heat activated precipitation were identified.
New materials are available for the well-known thermal process of 3D printing which involves consecutive deposition of layers of heated thermoplastics. Hence, machine components can be made not only from the most common plastics, such as ABS, but also from PLA, HIPS, PET, PVA, PETG, PC, and others. By means of 3D printing, intricate-shape parts can be produced in a flexible manner and prototypes can be easily fabricated from various thermoplastics. This paper demonstrates the use of a thermoplastic aliphatic polyester (PLA) for 3D printing of a part intended for operation under mild thermal loading. One of the advantages of PLA is its good degradability. This is because its production is based on the use of corn starch or dextrose. Despite that, PLA structures can be created which exhibit higher hardness and strength than the ordinary ABS.
Structurally complex phase analysis of TiNi-based alloys was carried out. The chemical composition of the prepared alloy was 49.5Ni-25.5Ti-10Zr-15Nb (at. %). The alloy was prepared by a vacuum induction melting and gravity casting. NiTi-based alloys belong to progressive materials which exhibit so called a shape memory phenomenon. These alloys are frequently used at high-temperature applications and automotive industry. The prepared alloy was examined by methods of optical microscopy, scanned electron microscopy, X-ray diffraction and thermo-evolution method of interstitial element analysis.
Twinning is an important deformation mode in materials with the hexagonal close-packed (hcp) structures. The shear deformation combined with shuffling of atomic planes can lead to a transition between the Mg hcp structure and a twinned hcp structure. Studying such a transition by means of ab initio methods should bring more insight into the twinning mechanism in magnesium where the {10-12} planes are the twinning planes. Comparison of ab initio results with those obtained using the semi-empirical embedded atom method is provided. It can help improve the fitted parameters of the embedded atom method.
This paper presents the results of epoxy laminate composites examinations. Laminates were reinforced with glass and also was modified using metallic powders with different granulations and content. The laminates are made of L-RTM technology using the laboratory test stand. The investigations contents static tension and dynamic tension. Flammability test, Charpy and impact resistance tests was also performed. The test results allowed for determine the effect of the amount, the type of particle on the achieved values in tests.
The dynamic superplasticity of aluminium alloys is considered from positions of the nonequilibrium phase transition theory. The macrokinetic analysis of mechanisms of superplastic deformation is carried out on the basis of the model representing stress, temperature and kinematic characteristics relationship, and energy state function is considered in the form of potential catastrophe assembling type. Analytical expression applied to function of sensitivity aluminum alloys to the structural transformations connected at superplasticity with the mechanism of dynamic recrystallization in the course of which grain is fining and the structure becomes fine-grained. The interrelation of this expression with the evolutionary equations of the model describing regularities deformation of alloys in the wide temperature strain-rate ranges, including superplasticity is presented.
The use of double sintering and rare-earth metal hydride additions allows us to substantially increase the hysteretic parameters of sintered permanent magnets having the composition ( wt %): Pr-14.7, Dy-16.9, Co-24.4, В-1.2, Al-0.3, Cu-0.15, Fe balance. The following magnetic characteristics were reached: Br = 9,5 кГс, jHc =20,5 кЭ, Hk =17,2 кЭ, BHmax = 22 МГс•Э, α = -0,01 (Т=-60-+1000С). The found weak dependence of structure-sensitive parameters, such as jHc and Hk on the cooling rate from the low-temperature heat-treatment temperature (5000С) is discussed in connection with the invar and magnetostrictive behavior of the principal magnetic phase (Pr,Dy)2(Fe, Co)14B at temperatures below the Curie temperature, which were used for the low-temperature treatment. Measurements of temperature dependences of the electrical resistivity of the magnets allowed us to demonstrate the presence and absence of the electrical-resistivity anomaly corresponding to the Curie temperature for magnets free from cobalt and with high cobalt content, respectively.
Ultra-fine grained (UFG) materials are in the spotlight because of their enhanced mechanical properties. Ti Grade 2 powder underwent attritor milling in liquid nitrogen (LN) and argon (LAr) and was consequently consolidated via spark plasma sintering (SPS). The influence of milling liquid (LN vs. LAr), of milling balls material (stainless steel vs. tungsten carbide) and of other milling parameters (e.g. speed, duration) on particle size and shape of powders; and chemical contamination, microstructure and microhardness of sintered samples was investigated. Particle size reduction was generally not observed, while their morphology changed significantly, probably because the powder was subject to simultaneous disintegration and intensive cold welding during the milling process. Using LN as a cooling medium resulted in very high nitrogen content (about 2.8 wt.%), and therefore in microhardness values up to 800 HV accompanied by extreme brittleness. LAr seems to be more suitable for milling of titanium, but a process control agent (stearic acid) must be added to prevent excessive cold welding. Microhardness rose from original 178 HV to the 200-300 HV range, depending on milling parameters.
The hydrogen storage properties of ball-milled Mg–Ti-Zr-C composite (1.8 wt% Ti and 1.9 wt% Zr and 0.2 wt.% C) were investigated. It has been previously shown, that the addition of Ti, Zr and C improved its storage properties. This beneficial effect of additives upon hydrogen storage properties can be explained by catalysis by the particles rich in Ti or Zr located on the surface of Mg grains. They provide effective pathways for the hydrogen diffusion into the MgH2. The morphological and microstructural characteristics were investigated by scanning electron microscopy and by X-ray diffraction. The hydrogen sorption was measured by Sieverts method using Setaram PCT-Pro device. In this paper, sorption behaviour of the composite after ball-millig and after ageing on the air was compared. The composite adsorbed 3.5 wt.% H2 within 10min at 623 K. However, sorption properties of the composite aged on the air for 7 months remarkably decreased: The aged composite adsorbed within 10min only 2 wt.% H2 at 623 K and the sorption capacity decreased from 4.64 wt.% H2 to 2.1 wt.% H2.
Lithium is a commodity undergoing through significant expansion recently. At present, lithium accumulators and batteries rank among very promising means for long-term accumulation of electricity. The main objective of this study was to obtain this metallic element from the feedstock from the locality Cínovec in the Ore Mountains. From the feedstock, we also managed to obtain rubidium and cesium. For materials obtained, detailed mechanical and physical characteristics was carried out, which includes e.g. friction parameters, material compressibility, or X-ray - diffraction. In the procedural part, magnetic separation was applied to obtain a good quality concentrate with the content of Li, Rb, and Cs. Subsequently, it was compared how mechanical and physical characteristics of the resulting products changed compared to each other and to the original material. It is clear from the first results that the choice of the process of magnetic separation to obtain a high-quality concentrate was very successful. The concentrates contained up to 1.4 % of Li, 0.9 % of Rb, and 0.02 % of Cs. Moreover, after separation, the angle of external friction of the resulting concentrate was reduced to a value of approximately around 18° in all samples. The compression index of the concentrate was twice as high as in the other measured samples, which corresponds to an average susceptibility of the material to compression.
Microstructure and mechanical response of joints of titanium and AISI 304 stainless steel performed using copper foil as an interlayer was evaluated in the study. The process was carried out in vacuum in the temperature range of 850 to 900 C for 60 min. The effect of temperature and cooling rate after processing stage on the microstructure and mechanical properties of the joints were analyzed by means of optical and scanning electron microscopy (SEM), electron probe microanalyses, microhardness measurements and tensile and shear strength tests. The maximum values of tensile and shear strengths were obtained for the joints processed at 900 C for 60 min. The cooling rate after bonding stage had significant influence on the microstructure and composition of the copper/titanium interface that could contain the eutectoid mixture of -Ti+CuTi2 or the undercooled -Ti solid solution. The difference in mechanical properties of joints slowly and rapidly cooled reached up to 25 MPa and increased with lowering joining temperature. Observation of fracture surfaces of the joints slowly and rapidly cooled demonstrated that failure took place through the eutectoid mixture or stainless steel/copper interface, respectively.
This paper discusses experimental results concerning the geometric accuracy of cylindrical holes made in EN AW-2007 aluminium alloy by a high-pressure jet of water containing almandine garnet as an abrasive substance. The tests were conducted according to a three-level Box-Behnken design using an APW 2010BB water jet cutting machine. The input variables were the cutting speed, the distance between the abrasive water jet nozzle and the workpiece, and the abrasive mass flow rate. Changes in the input parameters during high-pressure abrasive water jet cutting resulted in the occurrence of geometric inaccuracies, i.e. changes in the nominal value of the hole diameter.
Since the discovery of porous metallic materials numerous methods of production have been developed. Porous metallic materials can be made from liquid metal, from powdered metal, metal vapors, or from metal ions. The aim of the paper is to introduce casting methods of manufacturing of metallic foams with irregular cell structure. Metallic foams are materials with the broad applicability in many different areas (e.g. automotive industry, building industry, medicine, etc.). These metallic materials have specific properties, such as large rigidity at low density, high thermal conductivity, capability to absorb energy, etc.
The corrosion protection of Nd-Fe-B type magnets in service means a significant increase in life-time and their application possibilities, especially under wet atmospheres. This contribution deals with structure of permanent magnets based on Nd-Fe-B primarily and their resistance to corrosion using nickel and zinc coatings. Chemical composition and structure of three selected magnetic materials of type NdRE-Fe-B with protective Ni (Ni/Cu/Ni) or Zn electroplating coatings were investigated by light and scanning electron microscopy after demagnetization (400°C/0,5h). Structure before thermal influence was also studied by metallography for comparison. In the magnetic materials of NdRE-Fe-B type (NdPr-Fe-B, NdPrGd-Fe-B, NdPrDy-Fe-B) the phases with different concentration of Pr, Dy or Gd were detected, and small amount of Al, Co and Cu (partially replacing Fe) were also found out. Corrosion sensitive phases rich in Nd (Pr, Nd) were distributed along grains or/and at triple points of sintered powder particles of type (NdRE)2Fe14B as base ferromagnetic phase. Corrosion properties of protective coatings and base materials were studied by potentiodynamic polarization method, salt spray test, gravimetric method and microscopy observations, including thickness measurement of coatings. A higher resistance of combined Ni/Cu/Ni coating were confirmed in comparison with Zn one. Various pores (oval, angular, like micro-cracks) were observed in structure of tested magnetic materials. Intergranular damage (corrosion or fracture) of base magnetic materials was also observed in close proximity under coatings.
The work deals with the controlled gasification of castings from aluminium alloys. In troubled places of castings the thermal nodes that cannot be always fitted with risers and interior shrinkage with negative infuence on tightness and the mechanical properties of casting are formed. If a riser cannod be used for eliminating the negative impact then i tis possible to use the Probat Fluss Micro 100 product. The practical part of the work deals with the monitoring of controlled gasification which create as a result of adding the Probat Fluss Micro 100 product and titanium hydride in various proportions. Using the Probat Fluss Micro 100 a nucleating phase and then with the aid of titanium hydride the hydrogen are brought in the melt. With the aid of visual comparison the effect of controlled gasification is evaluated.
Nickel-rich part of ternary system Ni-Al-Cr is crucial for currently used nickel superalloys and alloys based on intermetallic phase Ni3Al. Those materials are dedicated to work at elevated temperature and consist, among others, of ordered phase γ′ and disordered phase γ in different proportions. Therefore, it is essential to learn high temperature course of phase boundaries γ′/γ′+γ and γ′+γ/γ in Ni-Al-Cr system. Series of alloys, which chemical composition from the Ni75Al25÷Ni65Cr35 section of discussed system, were prepared and were tested using high-temperature solution calorimeter. The device allows for determination of formation enthalpy of alloys at temperatures up to 1273K. Formation enthalpy of alloys from Ni75Al25÷Ni65Cr35 section was determined for three temperatures: 873K, 996K and 1150K. On the basis of changes in the enthalpy of formation value with increase of chromium content in alloys, presence of characteristic points was found. It was assigned to phase boundaries γ′/γ′+γ and γ′+γ/γ. Likewise, it was similar to previous ranges tested by author which is: Ni75Al25÷Ni75Cr25 and Ni75Al25÷Ni87Cr13.
We used for tests in compression at higher temperatures Ni3Al based alloys in the as-cast and directed state. The alloys were prepared by vacuum induction melting. Directional solidification was performed by Bridgman method with the vertical arrangement. In thus prepared samples we determined mechanical characteristics in compression at temperatures of 1000 °C and 800 °C with use of the equipment GLEEBLE 3800. Evolution of deformation of alloys in directed and as-cast state has a similar course, yet it is still possible to observe some differences. The alloys in the directed state show more stable evolution of deformation, whereas single-phase Ni-24Al alloys achieve better mechanical properties at higher temperatures. It was found that the yield strength increases up to the temperature of 800 °C. Single phase and multi-phase alloys in directed state exhibited at testing at the temperature of 1000 °C distinct yield strength, which is not typical for these alloys within the temperature range of 20-800 °C. The maximum obtained values of stress and yield strength of non-alloyed alloys based on Ni3Al achieve good values in comparison with a similar type of alloys.
Alloyed layers enriched with Zn and Al were fabricated on an Mg substrate using the powder-pack method. The Mg specimens were first immersed in Zn+Al powder mixtures serving as the source of diffusion elements and then heated at 440 oC for 60 min. The experimental results revealed that the microstructure of the alloyed layers was dependent on the composition of the powder mixture. The layer produced from a mixture containing 60% of Zn had a structure composed of an Mg17(Al,Zn)12 intermetallic phase, a solid solution of Al and Zn in Mg and a eutectic (Mg5Al2Zn2 intermetallic phase + solid solution of Al and Zn in Mg). When a mixture with a higher content of Zn (80%) was used, the layer had a structure composed of coarser eutectic areas (Mg5Al2Zn2 intermetallic phase + solid solution of Al and Zn in Mg) and fine-structured eutectoid areas (MgZn intermetallic phase + solid solution of Al and Zn in Mg). The layers containing intermetallic phases were characterized by high microhardness. The microhardness of the layers was five times higher than that of the Mg substrate.
Temperature dependence of internal friction Q-1(T) and elastic module E(T) (directional of inelastic-elastic body) and 2D, 3D AFM microstructure of VT3 Ti alloy after mechanical and thermal treatment is represented.
For ultrasound (US) devices USMV-KNU on frequencies f1 ≈ 1.67 MGz and f2 ≈ 5 MGz and computer Kern-4 on frequencies f║ ≈ 1,11 MGz and f┴ ≈ 0.43 MGz the measured velocity error is equal ΔV/V = 0.5÷1.5%.
The quasilongitudinal US velocity V║[001] = 5270 m/sec was determined from the oscilloscopegramma; elastic module E001 = ρ.V2║[001] = 75.26 GPa; “fast” quasitransversal US velocity V┴[100] = 2740 m/sec, shear module G100 = ρ.V2┴[100] = 18.84 GPa; after Puasson coefficient μ = 0.2996, Debye temperature θD = 267.0 К SiO2.
Thus, the measuring of IF background Q-10 after different heat, mechanical, radiation treatments gives information about the changing of the thermoelastic strains fields σi in Ag-Zn, Al, Ti alloys. The growth of heights IF maximums QM-1 testifies the growth of structural defects concentration, and the broadening of IF maximums ΔQM-1 here represents the relaxation process of structural defects new types in Ag-Zn, Al, Ti alloys. The correlation between elastic module Е, pressure P and temperature Т may be presented az surface (“directional surface of elasticity body”) before and after satiation, which gives additional information about influence of the saturation of solution.
Alloys of the intermetallic compound Ni3Al are commonly used at high-temperature applications up to a temperatures of approximately 800°C. It is caused by its structure (L12 type) which exhibits an anomalous behaviour – an increase of a yield stress with increasing temperature up to an aforementioned temperature. Unfortunately, the intermetallic compound Ni3Al is very brittle at room temperature. The brittleness is caused by atomic hydrogen which diffuses along grain boundaries and weakens their strength. The problem can be solved by using the intermetallic with hypo-stoichiometric concentration of aluminium alloyed with a small addition of boron. Boron preferably precipitates along grain boundaries and increases their cohesive strength.
Ni-22Al-0.5B and Ni-24Al-0.5B alloys (at. %) were prepared by the process of an induction melting in the argon atmosphere followed by a centrifugal casting. The castings were directionally solidified in a resistance furnace at the temperature of 1.550°C and the rate of a solidus-liquidus interface growth of 50 mm/h. The castings and the ingots after directional solidification were used for a preparation of samples for a compression test. The samples were shaped as short cylinders (812 mm). Compression tests were carried out at the temperature of 800°C. Gained results have confirmed that alloys alloyed with boron and after directional solidification have a higher yield stress than castings and unalloyed alloys.
Additive manufacturing (AM) is a promising technique for producing complex parts layer by layer from different metal alloys. Selective Laser Melting (SLM) consists of melting a previously formed powder layer by laser and fusing layers together according to the CAD-data. SLM is a promising method for producing custom-made implants from titanium powders due to the possibility of creating geometrically complex parts with high mechanical properties directly from the CAD-file.
In the presented work, a hip implant was manufactured by SLM from plasma atomized Ti-6Al-4V powder. Computer-tomography data of the patient's deformed bone structure was used for 3D-printing the patient's hip bone model from polyamide. Then an implant prototype was made from polymer accounting the anatomical features of the patient. The implant model was 3D-scanned to obtain a CAD-file of the implants, which was further improved using CAD-software by partial texting of its surface. Titanium implant was produced by SLM and then annealed to achieve the better combination of tensile strength and elongation by partial decomposition of martensitic phase, which allowed the mechanical properties of the produced material meet the requirements of ASTM F2924 for additively manufactured Ti-6Al-4V alloy and ISO 5832-3 Implants for surgery from titanium 6-aluminium 4-vanadium alloy. The hip implant has been succesfully installed to the patient. the postoperative supervision has shown a good result. Applying AM for producing the custom hip implant allowed to decrease the operation time and lessen the risk of the infection ingress.
Recently developed metastable alloy Ti–35.3Nb–7.3Zr–5.7Ta–0.7O (wt.%) abbreviated TNZTO is unique in its high oxygen content and exhibits promising properties for successful use in biomedicine, namely for total endoprostheses and bone fixation. High O content causes increased strength and, interestingly, good ductility with elongation > 15%. Tensile tests were performed on the as-cast material and material after high-temperature die forging. As-cast material showed yield stress > 800 MPa, whereas yield stress of die-forged material exceeds 1000 MPa. A series of as-cast samples was annealed at 400-500°C/1-16h. Alpha phase particles were observed by SEM only along original beta/beta grain boundaries. The microhardness tests were performed on the as-cast, die-forged and annealed conditions and compared with microstructure observed by light and scanning electron microscopy.
The article deals with casting methods of producing of metallic foams, it is focused on materials with a regular arrangement of internal cells. Currently, there are two areas dealing with metallic foams: optimization of already used casting technologies - manufacturing of metallic foams with a regular cell structure using sand cores and technology using evaporable pattern (lost foam). Cast metallic foams have a wide range of applications such as: construction, transport, heat exchangers etc. for their outstanding properties: reduced weight sufficient strength to absorb the impact energy or the possibility of heat conduction.
These days are more and more posing claims for the highest quality of castings from the aluminium alloys and for the lowest weight of these castings. These requirements force producers of such castings to utilize materials properties as much as possible. As one of such properties there is fatigue life which plays a crucial role at dynamically loaded parts. Dynamic working life depends on the many parameters such are loaded parts surface, structure and state of the residual stresses on the surface and so on. This paper deals with the utilization of the diffraction analysis at testing castings (specimens - rods) from the alloy AlSi7Mg0.3 that are poured into the metal mould after different thermal treatment methods. In this case was used diffraction analysis by means of the X-ray tensiometry and qualitative evaluation of structure by the Debey-Scherrer method (back-scattered). At the testing specimens was carried out analysis only on the surface by reason of the non-destructive determination of the residual stresses and real structure of specimens because testing specimens were subsequently tested by fatigue tests. One of the crucial parameters of fatigue life is the residual stress state on the loaded part surface and also its structure. Testing surface of all testing specimens was made by the same technology – turning by the CNC machine.
In the work the mechanism of the equilibrium crystallization of the alloys in the ternary system with the monovariant eutectic equilibrium has been investigated. New peculiarities of the equilibrium crystallization of the binary eutectics in the ternary systems have been found out. It is shown that the equilibrium crystallization of the binary eutectics in the ternary systems is going by the diffusion decomposition of the liquid phase (MDECOM) and the changing of the compositions of the previously precipitated solid phases to the new equilibrium one owing to the diffusion interaction with the liquid phase (MINTERAC). A new method of the graphic representation of the element phase equilibrium in the ternary system with the eutectic equilibrium is proposed. Analytical relations have been deduced which make possible to determine the main indices of the equilibrium crystallization of the binary eutectic alloys in the ternary systems MDECOM, MINTERAC, i – crystallization rate at the liquidus and solidus. Calculations of the equilibrium and non-equilibrium crystallization of the alloys in the Al-Si-Ge system were done using the Thermo-Calk program and experimental investigations of the alloys of this system were carried out.
The contribution is focused at assessing the influence of ALPORAS aluminium foam porosity on dimensional precision of machined workpiece using electroerosion wire cutting technology. The surface structure of material is formed by continuous nets of membrane material, pore volumes and cavities filled with gases residues after foaming. Due to the material structure cutting process is not continuous throughout whole material and electric discharge have to be initiated at the border of each pore in cutting line. This have an influence on the stability and accuracy. Deviations from the nominal dimension where measured, and for graphic representation the type A of standard uncertainty where calculated. From measured data the “barrel effect” can be determinate. Barrel effect can cause the edge of a wire cut part to have a “bow” or “belly” shape.
The study is centered on preparation and microstructural stability analysis of Cu composites containing different volume contents of secondary phases (MgO, Al2O3). The microstructure evolution is observed during the preparation of a nanocrystalline powder and after its processing into a compact. Effect of the dispersed oxide phases on preservation of the initial nanostructure is analyzed. The composites were prepared by thermo-chemical transformations of precursors (CuO + MgO, CuO+ Al2O3) and mechanical milling followed by spark plasma sintering technique. The microstructure development of the powders during their preparation and subsequent compaction is characterized by metallographic observations and X-ray diffraction analysis. Mechanical properties were tested by micro and macro hardness measurements. From the results follows that the Cu materials containing Al2O3 dispersoid exhibit improved thermal stability and higher hardness values compared to Cu materials dispersion strengthened by MgO particles.
Modular hip joint endoprostheses allow for fitting the head size and offset (distance from the centre of the head to the mechanical axis of the prosthesis) with the prosthesis size. This is possible through application of the external lock cone, mainly with dimensions of d = 12, L = 11, D = 14, and the internal cone with the same dimensions in the head. Proper mounting of the head on the stem causes a firm and stable fixation of the head-stem system.
It is essential for the analysis of the materials currently used for stems and heads with extremely varied strength parameters that their effect on intensity of wear of the head and stem is also taken into consideration. The examinations were based on the heads made of materials FeCrNiMnMoNbN, 316L, CoCr, Al2O3, ZrO2 which were in contact with stem materials such as Ti6Al4V, CoCrMo, 316L.
Based on the components removed from human body, it was demonstrated that the use of prosthesis causes micro-displacements on the contact surfaces of the stem and bone head and wear of these surfaces. Evaluation of wear was carried out based on the analysis of the surface geometrical structure (SGS) of the internal cone in the bone head. For this purpose, the measurements were conducted using GOM ATOS II 3D scanner. The results of the SGS measurements for the internal surface of the heads in contact.
The examinations of the artificial joints in modular endoprostheses showed the wear between the surfaces of the stem and head resulting from rotational and axial movements of the head on the stem cone. The magnitude and extent of the wear depend mainly on the patient's weight, intensity of use (physical activity), range of movement in the artificial joint and type of stem and head materials.
In present investigation diffusion bonded joints between titanium (Grade 2) and stainless steel (X5CrNi18-10) using 0.1 mm thick aluminum foil as a filler metal were produced at 600 ⁰C temperature for 60 minutes under: 2MPa, 4MPa, 6MPa and 8MPa pressure in vacume. The microstructure was investigated using light optical microscopy and scanning electron microscopy equipped with an energy dispersive X-ray system (EDS) to determine chemical composition of joint. Joining between dissimilar materials, results in formation of intermetallic phases in the interface. The FeAl3 and Fe2Al5 intermetallic layers were observed at the stainless steel-aluminum interfaces. At the aluminum-titanium interfaces TiAl2 intermetallic layers were identified. The investigation show that the pressure is important factor to control mechanical properties of diffusion bonded joints. The highest shear strength (88 MPa) was achieved for samples prepared using the highest pressure value, and for those samples were performed corrosion resistance test in 3% sodium chloride solution. the The samples were kept in the solution for 24, 48, 72, 96 h. Corrosion resistance of the diffusion brazed joints was evaluated by the weight loss during the test.
Nickel is essential metal due to usage area as stainless steel, non-ferrous alloy production, electroplating and chemical industry. Degradation of nickel sulphides leads to extraction of nickel from laterites. High cost equipment of high pressure acid leaching and since heap leaching needs longtime, atmospheric acid leaching of laterites becomes popular. Parameters of atmospheric leaching are important in terms of acid consumption, content of pregnant solution and residue. Therefore in this study, lateritic nickel ore from Manisa-Çaldağ/Turkey was leached for determining acid concentration parameter, both sulfuric acid and nitric acid – sulfuric acid mixture with varying percentage by volume. XRD analysis of lateritic nickel ore was showed that ore mainly consist of quartz and goethite. Pregnant leach solutions were analyzed with atomic absorption and leach residues were characterized by X-ray diffraction and scanning electron microscopy. Increment of acid concentration caused increased nickel content in the solution but iron content increased as well.
Selective Laser Melting (SLM), an additive manufacturing technology, shows a high potential for preparation of biomedical implants, especially from reason of its capability to achieve geometrically complex shapes. Therefore, a preliminary research was done in order to characterize microstructure and mechanical properties of titanium alloy Ti-6Al-4V, one of the most frequently used materials for orthopaedic implants. As results show, SLM yields comparable strength properties as the wrought material, thus makes it an appropriate manufacturing alternative. Only drawback is represented by reduced elongation associated with defect porosity, which can be, however, optimized by an ideal combination of process parameters. In conclusion, SLM has a good outlook for the preparation of customized medical devices exactly reproducing the patient’s defect being treated and porous implants with properties corresponding to human bone enhancing biological and mechanical fixation.
Aluminium alloys with higher content of alloying elements are very susceptible to the emergence of crystal segre-gation that significantly affects the mechanical, physical and chemical properties of these alloys. Crystal segrega-tion is called chemical heterogeneity in microscale and is formed during crystallization. Crystallization of alloys does not occur at a particular temperature, as is the case of pure metals, but in a certain temperature interval. During cooling of the melt occurs to formation of different regions within the dendritic cell that differs in chemi-cal composition. Generally is crystal segregation defined as chemical heterogeneity formed during alloy crystalli-zation that is enriched or deprived of alloying elements and impurities that segregate unevenly across the surface of the dendrites. In the central area of the dendritic cells is alloy deprived of alloying elements, while the outer parts of dendritic cells and in space between dendrites is the concentration of alloying elements richer. This con-centration has a hyperbolic course, when the central region of dendritic cells has the lowest concentration of the alloying elements and the outer part of dendrite boughs and interdendritic space have the maximum. Distribution of individual elements has a recurring character and can be described by sine function. The distance between two main axes of dendritic cells is affected by the temperature interval between the liquidus and solidus for the given alloy, the cooling rate of the melt and temperature gradient during solidification. Formation of the crystal segre-gation in aluminium alloys rich in alloying element and additives cannot be prevented, it is possible only influence its scope and with the right choice of heat treatment parameters can be suppressed. To suppress the crystal segre-gation the castings are subjected to heat treatment which is called homogenization annealing. It is the diffusion process in which there occurs to a balancing of chemical composition of alloy and the uniformity of its structure.
Ti-6Al-2Sn-4Zr-6Mo (Ti-6-2-4-6) is a high strength titanium alloy having low density and good corrosion resistance. The primary commercial applications of this alloy are forgings designed for working at intermediate temperature turbine engine rotating components. Currently the most common charge for forging is cast material. However, a promising alternative for producing such stock can be powder metallurgy (PM). This approach gives the opportunity to receive high quality products with fine microstructure and profitable mechanical properties. An application of Alexander-Malas criterion of plastic flow stability in reference to the investigated material makes possible predicting the material flow behaviour during hot processing as well as can be used as the basis for selection of the profitable parameters of forging. As the initial material for the investigations Ti-6-2-4-6 alloy compacts were used. The characteristics of hot deformation behaviour of Ti-6-2-4-6 alloy was studied using processing maps obtained on the basis of flow stress data, generated in compression tests performed at the temperature range of 800 – 1100oC and at the strain rate ranging from 0.01 s-1 to 10 s-1. Basing on elaborated criteria of plastic flow stability the processing maps for constant value of strain were developed. Complex processing map, describing the areas of flow instabilities and processing window, was also developed. The determined domains were interpreted taking into account criteria describing mechanical and microstructural stability of thermomechanical processing. The obtained results were correlated with representative microstructures of the samples deformed in hot compression tests.
The aim of this study is an investigation of fatigue properties and degradation development caused by cyclic loading in EN AW-2618A aluminium alloy fabricated by selective laser melting (SLM). Recently, the growing significance of aluminium as a constructural material is evident, and due to possibility of manufacturing parts with complicated geometry, it would be beneficial to be able to produce high-strength alluminium alloys using SLM. Sets of SLM specimens using different process parameters and specimens from extruded material with the same chemical composition were produced. Bending fatigue tests using symmetric cycle at different stress amplitudes were performed. During the tests acoustic emission (AE) was recorded in order to observe processes occurring in the material. Obtained AE signal was correlated with fractographic analysis. Fatigue tests showed that extruded material had significantly better fatigue performance compared to SLM. Moreover, fatigue resistance of SLM material is strongly dependent on process parameters settings and production conditions. AE signal analysis and fractography revealed that development of damage in SLM alloy was completely different from extruded material.
Magnesium and magnesium alloys, as the lightest structural metal available, have lately been in the focus of researchers due to the several excellent properties.
The use of magnesium alloys in industrial fields, such as the automotive and bicycle industries, has gained much attention due to their superior strength to weight ratio and low cost. Magnesium alloys owing their unique properties are considered also as an appropriate material for manufacturing biodegradable implants. The most beneficial would be shortened recovery time and save of the re-operation costs. However, the application of magnesium alloy is greatly limited for its relatively low strength, plasticity, rapid corrosion leading to the hydrogen accumulation in the surrounding area and to rapid deterioration of mechanical properties.
The main goal of my project is focused on the effect of termomechanical processing through ECAP on the microstructure, mechanical properties and corrosion properties. The investigation was performed on the extruded magnesium alloys WN43, commercial alloy, and on the states after one pass (1P), two passes (2P), four passes (4P) by ECAP. Mischmetal of rare earth elements, which are usually studied, has been replaced mainly pure yttrium and neodymium. Fine-grain structure with grain boundaries with high angle misorientation was achieved by this process. Processing also led to a decrease in corrosion resistance in this alloy. Microstructure development was characterized in detail by scanning electron microscopy. Development of mechanical properties was investigated by microhardness measurement. Corrosion resistance was investigated by linear polarization method.
The purpose of this work is to study the evolution of the microstructure and mechanical and electrical properties of an aluminum alloy, depending on the deformation level and time annealing processing. The study was conducted on a wire (as-received) AGS type aluminum used by the international company ENICAB of Biskra for electrical cabling. The wire, obtained by cold drawing, undergo annealing treatment at the temperature 170 ° C for different times of the holding (10 minutes, 4 hours, and 20 hours). Characterization methods used in the context of this work to study the evolution of the microstructure and to measure the mechanical and electrical properties are: optical and electron microscopy, micro-hardness, tensile test and measurement electrical resistivity. It was noted that the aluminum wire drawing causes an increase in the microhardness, which produces a high hardening of the material accompanied by a development of a fibrous texture. on the other hand the annealing to 170 ° C does not cause a noticeable change on the evolution of the mechanical strength and electrical resistivity by a port has the deformed state. By cons there has been a remarkable decrease in elongation after 4 hours at 170 ° C annealing by a port has the deformed state.by-against there has been a remarkable decrease in elongation after 4 hours of treatment at 170 ° C.
The main object of this article is to present methods of electrical waste sorting and the subsequent processing of its metallic component. The electrical waste grit is formed by crushing of electric current cable conductors and consists of pieces of copper wires and plastic granulate. The original sample was characterized by fundamental mechanical-physical properties, which are the angle of internal friction, density and morphology (shape and size distribution). Methods of electrical waste sorting were assessed on the basis of the obtained amount of pure copper component. This metal part of the sample was subsequently pelletized to facilitate re-use in the metallurgical industry. First results showed that the vibrating sieve method is in comparison with the pneumatic means for this purpose more efficient. Produced copper pellets showed good mechanical resistance and hardness. The advantage of densified metal component in the form of pellets appears to be easier fall into the melting furnace, without unnecessary losses, in contrast to the lighter, untreated copper wires with a high specific surface.
MAR-M-247 is a nickel-base superalloy developed for applications requiring high strength at elevated temperatures up to about 1000ºC. Its balanced composition provides an excellent combination of tensile and creep-rupture properties as a result of gamma-prime strengthening enhanced by solid solution and grain-boundary strengthening. MAR-M-247 has good castability. It is usually used for turbine blades and turbocharger wheels castings. Heat treatment is usually applied.
Different shape and weight of castings implies different conditions during solidifying and cooling resulting in different castings microstructure. When approving the castings, mechanical values are measured by tensile test on test bodies made from castings with different microstructure. This work investigates correlations between mechanical properties and microstructure, particularly grain size and texture, carbides, casting defects, and gamma-prime phase.