Interdendritic Areas Research Articles

The Effect of the Shielding Gas Flow Rate on the Geometry, Porosity, Microstructure and Mechanical Properties of Laser Weld Joints

Abstract In this research, studied was the microstructure of AW5083 aluminium alloy butt laser weld joint fabricated under the Ar + 30 vol. % He shielding gas. The light and electron microscopy, computed tomography, microhardness measurements and tensile testing were used for evaluation of the weld joint properties. Porosity volume in the weld metal (WM) was observed by the computed tomography (CT). The volume of porosity in the weld No. 1 was 0.05 mm3, while that in the weld No. 2 was 1.45 mm3. The width of the weld No. 1 was 4.69 mm, the average tensile strength was 309 MPa, and the average microhardness was 55.7 HV0.1. Polyhedral grains with an average grain size diameter of 48 μm were present in the heat-affected zone. The fusion zone (FZ) was of a dendritic structure with an average grain size of 20 μm. Three intermetallic compounds β-Al3Mg2, γ-Al12Mg17 and Al49Mg32, which were identified by transmission electron microscope (TEM) analysis, were present in inter-dendritic areas of the WM. The weld joint was characterized by ductile fracture in the base metal (BM). In the FZ, a small number of Al2O3 particles of irregular shapes were observed.

Influence of post-heat-treatment on the microstructure and fracture toughness properties of Inconel 718 fabricated with laser directed energy deposition additive manufacturing

The influence of post-heat-treatment on the resulting microstructure and room-temperature fracture toughness (KIC) of Inconel 718 fabricated by laser solid forming (LSF), a kind of laser based directed-energy-deposition additive manufacturing technologies, is investigated. Detailed microstructure characterization was performed on as-fabricated and heat-treated samples using direct aging (DA), solution treatment plus aging (STA), homogenization plus STA (HSTA), respectively. The results indicate that as-fabricated sample mainly consists of γ columnar dendrites and a small quantity of (γ+Laves) eutectics in the interdendritic areas. After DA post-heat-treatment, the nonuniform γ′′/γ′ precipitates exist around Laves phases. After STA post-heat-treatment, the short-acicular δ-phases precipitate around/in the Laves phases, the micro-segregation reduces and the distribution of γ′′/γ′ precipitates in the dendrite arm is almost homogeneous. After HSTA post-heat-treatment, Laves phase mostly disappears, micro-segregation completely removes and the γ′′/γ′ precipitates (~30 nm) are distributed in bimodal recrystallized grains. The results of KIC testing indicate that as-fabricated sample possesses the lowest KIC mainly due to its lowest elastic modulus and yield strength. However, the KIC of DA sample (~89.8 MPam) is close to that of as-fabricated sample, mainly due to its low ductility and strain-hardening exponent. But, the KIC of STA and HSTA samples increases by ~55.8% and 90.8% compared with as-fabricated sample respectively, mainly because of the better performance in strength–plasticity of HSTA sample (~1114 MPa, ~26.1%). Particularly, the KIC of HSTA sample with bimodal grains is ~60 MPam higher than the lower limit of wrought IN718 (AMS 5662) and reaches ~164.1 MPam. There exists significant difference in the KIC fractographs of as-fabricated and heat-treated samples. Overall, this research illustrates that an appropriate post-heat-treatment possesses obvious toughening effect on the LSF Inconel 718 alloy.

Influence of magnetically constricted arc traverse speed (MCATS) on tensile properties and microstructural characteristics of welded Inconel 718 alloy sheets

The magnetically constricted arc technique was implemented to mitigate the heat input related metallurgical problems in Gas Tungsten Arc Welding (GTAW) of Inconel 718 alloy particularly Nb segregation and subsequent laves phase evolution in fusion zone. This paper reports the direct effect of magnetically constricted arc traverse speed (MCATS) on bead profile, tensile properties and microstructural evolution of Inconel 718 alloy sheets joined by Gas Tungsten Constricted Arc Welding (GTCAW) process. The mechanism amenable for the microstructural modification and corresponding influence on the tensile properties of joints is investigated both in qualitative and quantitative manner related to the mechanics of arc constriction and pulsing. It is correlated to the solidification conditions during welding. The relationship between MCATS and Arc Constriction Current (ACC) was derived. Its interaction effect on the magnetic arc constriction and joint performance was analysed. Results showed that the joints fabricated using CATS of 70 mm/min exhibited superior tensile properties (98.39% of base metal strength with 31.50% elongation). It is attributed to the grain refinement in fusion zone microstructure leading to the evolution of finer, discrete laves phase in interdendritic areas.

Effect of boron on isothermal oxidation behavior of a nickel-base superalloy with high Al and Ti contents

The influence of boron on the oxidation resistance of conventionally cast U720Li alloy was investigated at 1130 °C and analyzed by X-ray diffraction (XRD), scanning electron microscope (SEM) equipped with energy dispersive X-ray spectroscopy (EDX) and electron probe microanalysis (EPMA). It has been found that the boron-undoped and -doped alloys all obey a super-parabolic rate law, but the oxidation rate is obviously increased by the boron addition. These alloys all show non-uniform oxidation between dendritic and interdendritic areas due to the serious microsegregation, while the oxide scale morphology of the high-boron alloy is quite different from that of the boron-undoped alloy. For boron-doped alloys, in the initial stage of oxidation the outward diffusion of boron from borides formed in the interdendritic region results in the formation of discontinuous and non-uniform B-rich oxide layers beneath and inside the Cr2O3 layer, while as the oxidation proceeds further boron can also transfer from the B-rich oxide to outer layers which eventually leads to disappearance of the B-rich oxide layers. The formation of B-rich oxide layers destroys the continuity of Cr2O3 layer and decomposition of B-rich oxide layers makes Cr2O3 layer more porous, which significantly reduce the protective property of the Cr2O3 layer and in turn decrease the oxidation resistance. Moreover, the eutectic (γ + γ′) highly enriched in Ti, Al is prone to be oxidized and form a thicker scale than the other regions, and hence the significant increase of its precipitation with boron addition also contributes to increasing the oxidation rate.

The Effects of Micro-Segregation on Isothermal Transformed Nano Bainitic Microstructure and Mechanical Properties in Laser Cladded Coatings.

The design of metastable retained austenite is the key issue to obtain nano bainitic steel with high strength and toughness. In this study, nanostructured Fe-based bainitic coatings were fabricated using laser cladding and following isothermal heat treatment. The microstructures and mechanical properties of the laser cladded coating were investigated. The results show that the Mn, Cr, Co, and Al segregated at the solidified prior grain boundaries. The micro-segregation of the solutes strongly influenced the stability of the austenite. As the isothermal temperature decreases, the interface of the bainite and blocky retained austenite approach to the prior interdendritic regions with the decreasing isothermal temperature, and the final volume fraction also decreases. The volume fractions of each phase and microstructure morphology of the coatings were determined by the interdendritic micro-segregation and isothermal temperatures. The stability of the blocky retained austenite distributed at the interdendritic area was lower than that of film and island-like morphology. This phenomenon contributed to the ductile and tough nano bainitic coatings with tunable mechanical properties.

Nano-devitrification and structural evolution of amorphous state in surface Ti-Ta-based alloy fabricated on TiNi substrate through additive thin-film electron-beam synthesis

Thin film metallic glasses (TFMGs) have a high application potential in MEMS industry. An important issue in ensuring the reliability of the functional properties of TFMGs (fatigue endurance, hysteresis-free response) is their thermal stability during operation. The problem of handling of the crystallization processes in the amorphous alloys is crucial for the understanding of structure-property relationships in the TFMGs. In this work, by liquid-phase mixing of the system [Ti-Ta film/TiNi substrate] using a low-energy high-current electron beam the surface Ti-Ni-Ta alloy (denoted as [Ti-Ni-Ta]SA) was fabricated. The thermal stability and crystallization behavior in the [Ti-Ni-Ta]SA upon devitrification were studied. According to the results of microstructural XRD/SEM/TEM analysis, in the as-received [Ti-Ni-Ta]SA a thin ~ 400 nm amorphous sublayer beneath the crystalline surface layer was observed. Devitrification of the [Ti-Ni-Ta]SA on heating at T = 773 K led to the formation of a nanocomposite structure, in which the phase composition was represented by a mixture of α"(Ti,Ta) martensitic phase, β(Ti,Ta) phase, precipitates of the η'-(Ti,Ta)2Ni intermetallic phase and a small amount of residual amorphous phase. The mechanisms of crystal nucleation and growth in an amorphous matrix were determined, and a scheme of phase transformations from an amorphous to a crystalline state was proposed. The crystallization of the amorphous phase occurred in two stages, including (i) the precipitation of primary β+α" grains and (ii) the growth of the β grains and the precipitation of η'-(Ti,Ta)2Ni intermetallic phases in the inter-dendritic areas, as well as in the interfaces by the eutectic crystallization mechanism.

Effect of Etching on Fatigue Properties of DD6 Single-Crystal Superalloy

The effects of etching on the surface integrities and the high cycle fatigue properties of DD6 single-crystal superalloy were investigated. The standard heat treated DD6 specimens were etched twice and four times using HCl/H2O2 solution, respectively, and the three-dimensional surface topography of specimens etched for different times was observed by Leica DCM8 confocal microscope and SEM. After that, the specimens with different surface states were subjected to high cycle fatigue testing at 760 °C and 980 °C in ambient atmosphere, respectively. The results showed that the surface of un-etched specimens had many longitudinal and parallel fine scratches which were caused by polishing, and the surface roughness was very low. Etching caused the occurrence of etching pits in the interdendritic areas, and with the increase in etching time, both the depth of the etching pits and the surface roughness increased. Moreover, the fatigue properties of the alloy were reduced after etching. The fatigue properties decreased with the increase in etching time. Etching was found to play a significant role on the high stress amplitude zone, while a smaller influence on the low stress amplitude zone. Compared with the results at 980 °C, the fatigue properties of the alloy at 760 °C were more affected by etching. The fatigue limits at 760 °C of the alloy after etching can be well predicted by the $$ \sqrt {\text{area}} $$ parameter model.

Improvement of microstructure and mechanical properties of TiAl−Nb alloy by adding Fe element

Abstract In order to improve mechanical properties and optimize composition of TiAl−Nb alloys, Ti46Al5Nb0.1B alloys with different contents of Fe (0, 0.3, 0.5, 0.7, 0.9, and 1.1 at.%) were prepared by melting. Macro/microstructure and compression properties of the alloys were systematically investigated. Results show that Fe element can decrease the grain size, aggravate the Al-segregation and also form the Fe-rich B2 phase in the interdendritic area. Compressive testing results indicate that the Ti46Al5Nb0.1B0.3Fe alloy shows the highest ultimate compressive strength and fracture strain, which are 1869.5 MPa and 33.53%, respectively. The improved ultimate compression strength is ascribed to the grain refinement and solid solution strengthening of Fe, and the improved fracture strain is due to the reduced lattice tetragonality of γ phase and grain refinement of the alloys. However, excessive Fe addition decreases compressive strength and fracture strain, which is caused by the severe Al-segregation.

The effect of iron on the microstructure and mechanical properties of a cast Cu–12Sn-1.5Ni (wt. %) alloy

Effect of Fe content on microstructure and mechanical properties in a gravity-cast Cu–12Sn-1.5Ni (wt. %) alloy has been investigated. Addition of 0.053, 0.63 and 1.44 wt % Fe caused grain refinement, vanishment of continuous interdendritic δ phase, and formation of nano-sized iron precipitates within the dendritic matrix. There was a simultaneous increase in the yield and tensile strength, uniform and total elongation and hardness of Cu–12Sn-1.5Ni-(0.05–1.5)Fe alloys relative to their Fe-free counterpart. Fracture surface analysis revealed an intergranular fracture along the interdendritic δ phase in Cu–12Sn-1.5Ni alloy. But in Cu–12Sn-1.5Ni-(0.05–1.5)Fe alloys, after initiation at interdendritic area, crack propagated into the dendrite matrix in a dimple rupture mode. The evolution mechanism of mechanical properties upon alloying content was discussed in terms of the microstructure characterization, analysis of strain-hardening rate, fractographic examination, as well as the strengthening model. This work sheds light on the alloying effect of minor Fe below 1.0 wt % on the microstructure-mechanical optimization in tin bronze alloys.

Numerical investigation of grain refinement of magnesium alloys: Effects of cooling rate

Solidification experiment of Mg-4Y-3Nd-1.2Al (wt%) alloy cast in a step-like sand-mold casting shows that a slow cooling rather than a fast cooling leads to grain refinement during solidification with in-situ formed nucleant particles (Al2RE) in molten melt. A two-dimensional cellular automaton (CA) model is adopted to fundamentally understand the mechanism of grain refinement. Conservation equation of energy is solved at macro-scale. The generated thermal history serves as input for the CA simulation. The model predictions are verified against the experiment. A high cooling rate leads to fast dendrite growth and solute enrichment in the interdendritic region. The nucleant particles, in-situ formed under the fast cooling condition, have small sizes. A larger number of small-sized particles are suppressed because they do not experience enough constitutional undercooling to nucleate. A critical particle size exists, above which the grain refinement becomes less sensitive to the cooling rate measured in the experiment. The simulation of one particle transported to the interdendritic area shows it is more difficult for this particle to develop under the faster cooling condition. We expect this fundamental understanding of the physics of cooling rate for the grain refinement would have implications on future complex magnesium alloy designs as well as solidification process control.

Gradient transition zone structure in “steel–copper” sample produced by double wire-feed electron beam additive manufacturing

This paper describes the results of an investigation into a microstructure formation on a wire-feed electron beam additive manufactured “steel–copper” bimetallic sample. The peculiarities of a gradient zone structure with a smooth change of components’ concentration are revealed. The heterogeneity of copper and steel distribution in the gradient zone is provided by copper solidification and precipitation mechanisms. Both solidification of coarse copper inclusions in the interdendrite areas or along the dendrite boundaries and precipitation of fine Cu-based particles at the cooling stage from the solid solution of Cu in γ-Fe are the main factors of structure formation during the double wire gradient zone deposition. The presence of such fine copper precipitates from the supersaturated solid solution was revealed by means of transmission electron microscopy. The shape of copper particles in the gradient zone varies from spherical to oblong and irregular. The shape of steel particles and/or grains is mainly determined by the peculiarities of the crystallization zone and is characterized by the primary crystallization of γ-iron dendrites from the liquid melt. A physical scheme describing a variation in phase composition and microstructure in gradient zone of the bimetallic specimen was proposed.

Influence of pore characteristics and eutectic particles on the tensile properties of Al–Si–Mn–Mg high pressure die casting alloy

Heterogeneous microstructure and unpredictable porosity distribution in Al–Si high-pressure die-castings give rise to a significant variation in their mechanical properties. This study investigated the influence of porosity distribution, volume of the largest pore, eutectic phase morphology and Mn-containing intermetallics on the tensile properties of Al–Si–Mn–Mg high-pressure die-castings. The as-cast material has a “network” of fine coralloid eutectic Si as well as blocky AlSiFeMn intermetallics in interdendritic area. The solution treatment step of the T7 heat treatment spheroidized the eutectic silicon. Tensile samples were tested in both the as-cast and T7 conditions. The yield strength (YS), ultimate tensile strength (UTS) and elongation (%E) of as-cast samples were in the ranges of 129–146 MPa, 242–282 MPa and 2.6–4.7%, respectively. After T7 heat treatment the YS, UTS and %E had ranged from 124-142 MPa, 195–207 MPa and 4.6–12.1%, respectively. The T7 heat treatment had little effect on the YS but reduced the UTS considerably. The enhanced %E can be ascribed to the spheroidization of eutectic Si. The largest pore by volume in the sample also plays an important role in determining the ductility according to three-dimensional (3D) pore morphologies obtained via computed tomography (CT). The sample with largest pore by volume has the lowest %E, indicating the %E can be estimated prior to tensile test based on the size of the largest pore by volume in the sample.

Advanced microstructural characterisation of cast ATI 718Plus\xae\u2014effect of homogenisation heat treatments on secondary phases and repair welding behaviour

The influence of base metal conditions on the weld cracking behaviour of cast ATI 718Plus® is investigated by comparing 4 h and 24 h dwell time pseudo-hip homogenisation heat treatments at 1120, 1160 and 1190 °C with the as-cast microstructure. Scanning electron microscopy (SEM), X-ray diffraction (XRD) on electrolytically extracted powder and transmission electron microscopy (TEM) were used to identify Nb-rich secondary phases in interdendritic areas as the C14 Laves phase and Nb(Ti) MC-type carbides. All homogenisation heat treatments but the 1120 °C 4-h condition dissolve the Laves phase. A repair welding operation was simulated by linear groove multi-pass manual gas tungsten arc welding (GTAW). The Laves phase containing microstructures resulted in lower total crack length for heat affected zone cracking. Constitutional liquation of Nb(Ti) MC-type carbides is observed as a liquation mechanism in Laves-free microstructure, while thick liquid film formation due to the Laves eutectic melting could reduce the formation of weld cracks in microstructures containing the Laves phase.

The influence of iron impurities on the compression behaviour of Al-2.24Mg-2.09Li alloy

As a major impurity element in aluminium-lithium (Al-Li) alloys, iron (Fe) reduces formability, fracture toughness, and fatigue resistance by solidifying into Al6Fe and Al3Fe particles. The research was performed in order to estimate the influence of Fe impurities on the compression behaviour of Al-2.24Mg-2.09Li alloy. The investigation was performed on the samples in as cast and solution hardened condition. The solution hardening was applied to improve the mechanical properties by dissolving intermetallic particles and enriching ?Al matrix with Mg. However, the higher strength properties and temperature increase during the compression testing were observed in as cast condition. Microstructural investigation revealed significant differences in microstructure changes between the samples in as cast and solution hardened condition. In as cast sample the barrelling effect led to the unequal deformation and surface texture development. The eutectic Al3Fe particles located in the ?Al interdendritic areas did not significantly impact microstructure changes. Although the solution hardening led to enrichment of ?Al matrix with Mg and Fe, the Al3Fe particles were not dissolved. The coarse morphology of Al3Fe particles and location at the grain boundaries of ?Al grains contributed to low energy intergranular fracture. The fracture nucleation and propagation across the grain boundaries resulted in lower strength values.

ANALYSIS OF THE PROPERTIES OF AW2099 ALUMINIUM-LITHIUM ALLOY WELDED BY LASER BEAM WITH AW5087 ALUMINIUM-MAGNESIUM FILLER MATERIAL

EN AW2099 aluminium lithium alloy, 2.0mm in thickness, was used as an experimental material. EN AW2099 belongs to the 3rd generation of aluminium lithium alloys. The third generation was developed to improve the disadvantages of the previous generation, such as anisotropy in mechanical properties, low fracture toughness, corrosion resistance and resistance to fatigue crack growth, as well. Aluminium magnesium 5087 filler wire with a diameter of 1.2mm was used for the welding. Crack free weld joints were produced after an optimization of welding parameters. The microstructure of weld metal and mechanical properties of weld joints were investigated. Equiaxed zone (EQZ) was observed at the fusion boundary. The character of grains changed in the direction towards the weld centre, from the columnar dendrite zone to equiaxed dendrite zone in the weld centre. The microstructure of the weld metal matrix consisted of -aluminium. Alloying elements enrichment was found at the inter-dendritic areas, namely copper and magnesium. The microhardness decrease in the weld metal due to a dissolution of strengthening precipitates was measured. The microhardness was slightly higher in comparison to a weld produced by a laser welding without a filler material. The tensile strength of the weld joint reached around 67% of the base material’s strength and the fracture occurred in the weld metal.

Microstructural characterization of laser-cladded NiCrAlY coatings on Inconel 625 Ni-based superalloy and 316L stainless steel

A detailed characterization of the primary microstructure of laser-cladded NiCrAlY coatings deposited on two different substrate materials is presented in this article. Amdry 962 powder was used to deposit coatings by LENS (Laser Engineered Net Shaping) on Inconel 625 Ni-based superalloy and 316L stainless steel. An overall characterization of coatings was performed from a qualitative point of view with particular attention paid to cracks and pores. A description of microstructural aspects of the internal morphology of coatings, such as the microstructure, chemical, and phase composition were also investigated. The distribution of alloying elements, such as Fe, Mo, Nb, and Y, was investigated in cladded coatings on two different substrates. It was revealed that the cladded coatings contained cracks and gas voids typical for laser-cladding processes. The dendritic microstructure was the result of rapid solidification due to differences in the chemical composition of dendritic and interdendritic areas, which was related mainly to the yttrium concentration. Additionally, epitaxial growth during the initial stages of solidification was determined to be related to the diffusion of substrate alloying elements into the dilution zone. The strong influence of substrate materials, especially iron, in the final microstructure of coatings was analyzed. The oxidation of yttrium and the formation of Y-Al-O oxides were also analyzed.

Influence of composition and as-cast structure on the mechanical properties of selected high entropy alloys

The paper investigates the influence of several alloying elements (Al, Mn, Cu, Ti and Si) and the typology of the as-cast structure on the mechanical properties of high entropy alloys. A theoretical criteria analysis was carried out on the Al–Cr–Cu–Fe–Mn–Ni, Al–Cr–Co–Fe–Ni–Ti, Al–Cr–Fe–Mn–Ni and Al–Cr–Cu–Fe–Mn–Ni–Si alloy systems to select appropriate compositions for application requirements. The alloys were prepared by induction melting and were cast in copper mold. As-cast samples were characterized by optical microscopy, scanning electron microscopy, X-ray diffraction and mechanical analyses. The experimental results partially validated the criteria predictions. Alloys with higher Al content presented most predominantly BCC type phases. Ti and Cu were found enriched in the interdendritic area. Si influenced greatly the as-cast morphology of the dendrite structure. The substitution of Co with Mn generated a significant improvement of the mechanical properties. A composition-structure-properties correlation was described in the paper. The morphology of the as-cast structure had a strong impact on the final properties of the alloys. The Al–Cr–Fe–Mn–Ni alloy showed the best overall characteristics, with a hardness of 412 HV and a compressive strength of 895 MPa.

A Comparative Study on Microstructure and Mechanical Properties of Ti‐43/46Al–5Nb–0.1B Alloys Modified by Mo

To improve mechanical properties of TiAl–Nb alloys and obtain effects of Al content on microstructure, Ti‐43/46Al–5Nb–0.1B–xMo alloys are prepared. Phase constitution, macro‐/microstructure volution, and mechanical properties of them are investigated systematically and compared in detail. Results show that the lamellar colony size refines, B2 phase increases and Al‐segregation in interdendritic regions aggravates with the increase in Mo content. The increased B2 phase is attributed to the increased Mo segregated at the grain boundaries during β/α transformation, and the aggravated Al‐segregation is attributed to the increased Al rejected into the interdendritic areas during L/β solidification. Compressive results show that the strength and strain increase about 150 MPa and 6% when the Mo content increases to 0.8 at% for Ti‐43Al–5Nb–0.1B–xMo alloys; they increase about 343 MPa and 4% when Mo content increases to 1.2 at% for Ti‐46Al–5Nb–0.1B–xMo alloys. Both the strength and strain decrease when Mo content further increases. The grain refinement strengthening and solid solution strengthening caused by Mo are contributed to the improved strength and strain. However, excessive B2 phase and severe Al‐segregation deteriorate the mechanical properties of the alloys, which act as the cracking sources.

Microstructure evolution and mechanical behavior of Al–Li alloy fabricated by laser melting deposition technique

This paper systematically studies the microstructure evolution, tensile property and microhardness of Aluminum-lithium (Al–Li) alloy with dimension of 80 mm × 30 mm × 80 mm manufactured by laser melting deposition (LMD) technology. Results indicate that the microstructures of the as-deposited Al–Li alloy are variable from the top to the bottom of the plate. At the top region, a fully dendritic structure is observed with underdeveloped secondary arms. And the copper-rich precipitates with irregular stripe morphology appear in the inter-dendritic areas. Attributing to the thermal cycle during laser deposition process, as distance increasing away from the top, the number of irregular stripe phases reduces with the massive precipitation of needle-like TB phases (soft and brittle). At the bottom of the plate, dendritics of as-deposited Al–Li alloy obviously coarsened, TB phases fully decorate the entire grains with a few residual copper-rich precipitates. Attributing to the different microstructures, the micro-hardness firstly increases from 121 HV to 134 HV at a distance of 30 mm, and then decreases to about 98 HV at the bottom of the deposited Al–Li alloy plate. The ultimate tensile strength of the as-deposited Al–Li alloy (longitudinal direction, at the middle-bottom part of the plate) is comparable to the hot-rolled Al–Li alloy (244 MPa). However, the yield strength and elongation of the as-deposited Al–Li alloy are relatively poor due to the embrittlement of copper-rich phases as well as TB phase.

ANALYSIS OF PROPERTIES AND TRIBOLOGICAL WEAR OF THE Co-Cr ALLOYS USED FOR PROSTHETIC CONSTRUCTIONS

The paper presents the results of investigations performed in the scope of the tribological wear of prosthetic cast alloys Co-Cr with micro-additions Mo and W. Abrasive wear resistance tests were carried out by means of a T-05 tester in the roller-block friction system in dry sliding metal-metal contact. A qualitative and quantitative evaluation of the alloy microstructure was made in correlation with hardness and abrasive wear. The analysis of the abrasive wear resistance of the examined alloys included an analysis of such parameters as the relative mass loss of the sample, the mean friction coefficient value, and the wear depth. It was established that the examined alloys Co-Cr-Mo-W are characterize by a low value of the friction coefficient, independent of the tribological test duration, which points to the lack of changes in the wear mechanism with the increase of the test duration time. The abrasive wear resistance of the tested materials are related to the morphology of the phases at the alloys microstructure after the solidification. A similar width of the interdendritic areas results in a similar degree of mass loss for the examined materials.