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In order to facilitate the prediction of some physical properties, we propose several simple formulas based on two parameters only, the metallic valence and metallic atomic radii. Knowing the composition, for single-phase alloys, the average parameters can be calculated by the rule of mixture. The input parameters can be obtained from tabulated databases. Adopting from the literature the results of Coulomb crystal model for metals and single-phase high-entropy alloys, we have derived formulas for the shear modulus (G) and the cohesion energy (Ecoh). Based on these parameters separately, we set up two formulas to estimate the hardness in the case of pure metals. For single-phase (solid-solution) HEAs, by simplifying the Maresca and Curtin model, we obtained a formula for estimating the hardness, which takes into account the atomic misfit in addition to G. The maximal hardness for single-phase HEA is approximately 600 kg/mm2 and is obtained for a composition with a valence electron concentration of approximately 6 ÷ 7. [ABSTRACT FROM AUTHOR]

To explore a new method to improve the wear resistance of TiNi shape memory alloy (SMA), Ti-50.8Ni alloy was treated by the method of ultrasonic surface shot peening. The microstructure evolution, hardness, and tribological behaviors have been further investigated to evaluate the effect of ultrasonic surface shot peening (USSP). The surface microstructure can be refined to some extent while the basic phase composition has little change. USSP can facilitate the martensitic transformation in the surface layer, which benefits improving the surface hardness. Additionally, the hardness of Ti-50.8Ni alloy increases first and then decreases with the increase of applied load, but the USSP-treated alloy tends to be more sensitive to load. USSP treatment can improve the wear resistance and reduce the coefficient of friction (COF) in case of a low sliding wear speed of 5 mm/s. However, the tribological properties of USSP-treated alloy are reversely worse in the case of 10 mm/s. This is mainly attributed to the combined effect of stress-induced martensite transformation and degeneration resulting from the frictional heating during the dry sliding wear process. [ABSTRACT FROM AUTHOR]

Fe‐0.3C‐15Cr‐1Ni high hardness corrosion‐resistant alloy coating is prepared on the surface of 3Cr13 by laser cladding technology. The effects of scanning speeds on the microstructure, microhardness, and corrosion resistance of the coating are studied. The results show that the microstructure of the cladding layer is mainly composed of intracrystalline martensite and carbides distributed along the grain boundaries. When scanning speed increases from 3 to 5 mm s−1, the grain is obviously fined, and the number of carbides increases, further increasing scanning speed, the grain refinement degree decreases and the carbide quantity decreases gradually. When scanning speed is 5 mm s−1, the microhardness reaches the maximum, the corrosion resistance is significantly improved at 5 and 7 mm s−1, and the pitting potential and passivation zone width increase by 180–219% and 69–78%, respectively, compared with 3 mm s−1 sample, but further increases scanning speed to 9 mm s−1, the hardness and corrosion resistance significantly reduce. This is because scanning rate affects the component undercooling degree of the dynamic molten pool and the temperature gradient at the solidification interface front, which affects the growth of dendrites, the number of carbides, and further affects the alloying elements in the carbide and matrix. [ABSTRACT FROM AUTHOR]

Pb plays an important role in determining the morphologies and mechanical properties of the Mg2Si phase in Mg-2.5Si-xPb alloys. As the amount of Pb increases from 0.4 wt.% to 1 wt.%, the primary Mg2Si phase is refined during solidification. Its morphologies transform from equiaxed-dendrite to polygonal and finally to roughly circular. The key reason for morphology evolution is the preferential adsorption of Pb atoms on Mg2Si {100} surfaces to suppress the growth rate along the ⟨100⟩ directions, which is demonstrated by the adsorption model based on first principles. In addition, the hardness of the Mg2Si phase decreases with the increasing solution content of Pb according to the results of the nanoindentation. With the addition of Pb at 1 wt.%, Pb content in the primary Mg2Si phase reaches a maximum of 0.4 wt.%, and the hardness of the primary Mg2Si phase reaches a minimum of 3.64 GPa. This reduction in hardness is attributed to the augmented ionic bond ratio resulting from the solution of Pb, which concurrently enhances the toughness of the Mg2Si phase. [ABSTRACT FROM AUTHOR]

This work has studied the co-addition of Sc and Zr elements into the Al-1.75wt%Fe-1.25wt%Ni eutectic alloy. The changes in the microstructure, electrical conductivity, and Vickers hardness of the Al-1.75wt%Fe-1.25wt%Ni-0.2wt%Sc-0.2wt%Zr alloy during heat treatment were studied. The results showed that two-step aging can effectively improve the aging response of the alloy over the single-step aging method. This was ascribed to the minimization of the diffusion difference between Sc and Zr elements. Furthermore, the homogenization treatment can also improve the aging response of the alloy by alleviating the uneven distribution of Sc and Zr. Nevertheless, the micro-alloyed elements exceeded the solid solubility limit in the Al-1.75wt%Fe-1.25wt%Ni-0.2wt%Sc-0.2wt%Zr alloy, and their strengthening effect has ever achieved the best prospect. Finally, both Sc and Zr contents were reduced simultaneously, and the aging response of the Al-1.75wt%Fe-1.25wt%Ni-0.15wt%Sc-0.1wt%Zr alloy was improved by optimized heat treatment. The underlying mechanisms for this alloy design and the corresponding microstructure–mechanical property relationship were analytically discussed. [ABSTRACT FROM AUTHOR]

Weight reduction is one of the prime goals for auto industries to achieve fuel economy, and magnesium matrix composite offers the opportunity to assist with fulfilling those needs. The present work focuses on developing the magnesium alloy (AZ91D), AZ91D/SiCnp nanocomposite, and AZ91D/SiCnp/CNT hybrid nanocomposite via the semisolid stir casting technique incorporating the ultrasonic vibration process. The produced cast samples are subjected to physical, microstructural, and mechanical characteristics study. The evaluated results are compared and it was found that AZ91D/6wt% SiCnpnanocomposite offers high hardness (78.45 ± 0.1 Hv), yield (150 ± 1.8 MPa), and ultimate tensile strength (241 ± 1.75 MPa) as compared to the cast AZ91D alloy samples. The scanning electron microscope reveals the homogeneous particle distribution structure with reduced porosity. The density of the developed composite obeys the rule of the mixture, and the porosity is limited to less than 1%. The presence of 6 wt% carbon nanotube in AZ91D/6wt% SiCnp alloy nanocomposite facilitates superior hardness, yield, and tensile strength of 84.35 ± 0.1 Hv, 174 ± 1.5 MPa, and 271 ± 1.6 MPa. The impact strength of the composite increased, while the content of SiCnp was improved. [ABSTRACT FROM AUTHOR]

This study explores the combined potential of severe plastic deformation (SPD) via differential speed rolling (DSR) and plasma electrolytic oxidation (PEO) to enhance the material performance of 6061 Al alloys. To this end, DSR was carried out at a roll-speed-ratio of 1:4 to obtain ~75% total thickness reduction and a final microstructure of <1 µm. The rest of the samples were annealed to obtain various grain sizes of ~1, ~25, and ~55 μm. Through DSR, the hardness of the material increased from ~64 to ~102 HV. Different grain sizes altered the plasma behavior which further influence the growth of the coating layer, where the fine grain size produced a compact structure beneficial for corrosion protection. This synergy offers tailored materials ideal for high-performance applications across diverse industries, combining enhanced bulk properties from DSR with optimized surface attributes from PEO. [ABSTRACT FROM AUTHOR]

Friction and wear are two critical tribological factors that instigate unavoidable failures of moving components in the mechanical system. Additionally, these factors have a huge impact on global energy consumption, economy, and CO 2 emissions. Minimization of friction and wear in mechanical systems is rather challenging, however, significant advancement has been achieved in the development of new techniques to mitigate these tribological issues. Surface coating is one of the most commonly used techniques to reduce/eliminate tribological failures. Though a wide range of hard and anti-wear coating materials (metallic alloys, carbon, metallic glasses, polymers, ceramics, and composites) have been developed in the last few decades, however, ceramic coatings have always been a prime interest to researchers owing to their outstanding hardness, wear resistance, corrosion resistance, and damping capacity. Specifically, nitride ceramic coatings have been passed a long journey as hard and wear-resistance protective coatings in multiple industries such as manufacturing, automobile, aerospace, etc. This article reviews the journey of the development of nitride coatings for tribological applications. These developments include first-, second-, and third-generation nitride ceramic coatings, which include binary, ternary, multi-elemental as well as multi-layered coating compositions. This review paper sheds light on the available literature, merits, demerits, and applications of all nitride ceramics coatings for tribological applications. Recently, an innovation in nitride ceramic coatings has been reported, which is the utilization of the high entropy concept in these coatings, which has been reported to improve their tribological properties tremendously. This review paper also delivers a comprehensive review of high-entropy nitride ceramic coatings (both equimolar and non-equimolar compositions) for tribological applications, which is the latest and hot topic for researchers working on ceramics coatings and tribology. At last, this review paper identifies the gaps and provides the future possibilities of research in this area. [ABSTRACT FROM AUTHOR]

The influence of severe plastic deformation, namely twist-channel angular pressing on the formation of quasicrystalline precipitates in Al–Mn–Zn–Ga alloy, was investigated. The deformation process was performed at two temperatures: 473 K (200 °C) and 433 K (160 °C). The microstructure of alloys after the process was analyzed in terms of the number density of formed precipitates, their size, and crystals structure. Mechanical properties including hardness and compression yield strength were determined. The obtained results indicated that at higher temperature (473 K), crystalline precipitates were formed. Additionally, the number density of the formed precipitates decreased with subsequent passes. At lower temperature, 433 K, the formed precipitates have quasicrystalline structure. Alloys processed at 433 K exhibit yield strength two times higher than in the previous case which correlates well with higher number density of precipitates estimated for these samples. [ABSTRACT FROM AUTHOR]

In recent decades, the requirements for plain bearing materials have continually increased, especially with new applications such as wind turbines, which require larger bearings. These new applications have completely different property profiles compared with, for example, bearings in automotive construction. Larger bearings need high strength and wear resistance, which established bearing materials cannot fulfill. Therefore, new alloy systems are required. This publication focuses on the influence of alloy composition and test temperature on the mechanical properties of ZnAlCu alloys. Centrifugally cast specimens were produced for the fabrication of test specimens, which were used to determine the mechanical and tribological properties. Fracture surface and wear trace analysis with scanning electron and light microscopy were used to determine occurring failure and wear mechanisms and to analyze the influence of microstructure on failure. Depending on the composition of the ZnAlCu alloys, up to three times higher strengths can be achieved compared with the white metal alloy SnSb12Cu6ZnAg. Furthermore, all the alloys investigated show good wear properties. Up to 11 wt.% aluminum and 1.5 wt.% copper, a significant decrease in the wear coefficient was observed. Knowledge about the correlation between microstructure, properties, and failure mechanisms of ZnAlCu alloys can be used to produce bearing metal alloys suitable for a wide range of applications. Since the strength values lie between those of white metals and bronze, new fields of application can also be accessed. [ABSTRACT FROM AUTHOR]

This research investigates the Al-4wt%Cu alloy, renowned for its significant mechanical properties, using both numerical simulations and experimental methods. The study focuses on the heat treatment process of the alloy, involving an extended duration ranging from 8 to 30 hours at a temperature of 500℃, followed by a reduction to 195℃ to alleviate residual stresses. Key to this process is the utilization of Brunel hardness equipment and a fatigue testing apparatus employing a bending load. The investigation extends to a mathematical simulation, elucidating the process of copper separation via deposition in aluminum and the subsequent phase transformation, which results in optimal mechanical properties. Further, the fatigue testing procedure for the alloy is simulated using the Auto Desk Inventor program. Results from the experimental phase indicate that a 12-hour treatment duration yields superior mechanical properties, with a recorded hardness of 260 Brunel and a strength of 200 MPa. In parallel, the numerical simulation results, exhibiting a strength of 195.7 MPa, demonstrate a notable convergence with the experimental findings, factoring in a correction factor of 0.96. This study not only underscores the efficacy of the optimized aging process in enhancing the alloy's mechanical attributes but also bridges the gap between theoretical predictions and experimental outcomes, providing a comprehensive understanding of the alloy's behavior under varied treatment conditions. [ABSTRACT FROM AUTHOR]

With the goal of developing lightweight Al-Ti-containing multicomponent alloys with excellent mechanical strength, an Al–Ti–Cu–Co alloy with a phase-separated microstructure was prepared. The granulometry of metal particles was reduced using planetary ball milling. The particle size of the metal powders decreased as the ball milling time increased from 5, 7, to 15 h (i.e., 6.6 ± 6.4, 5.1 ± 4.3, and 3.2 ± 2.1 μm, respectively). The reduction in particle size and the dispersion of metal powders promoted enhanced diffusion during the spark plasma sintering process. This led to the micro-phase separation of the (Cu, Co)2AlTi (L21) phase, and the formation of a Cu-rich phase with embedded nanoscale Ti-rich (B2) precipitates. The Al–Ti–Cu–Co alloys prepared using powder metallurgy through the spark plasma sintering exhibited different hardnesses of 684, 710, and 791 HV, respectively, while maintaining a relatively low density of 5.8–5.9 g/cm3 (<6 g/cm3). The mechanical properties were improved due to a decrease in particle size achieved through increased ball milling time, leading to a finer grain size. The L21 phase, consisting of (Cu, Co)2AlTi, is the site of basic hardness performance, and the Cu-rich phase is the mechanical buffer layer between the L21 and B2 phases. The finer network structure of the Cu-rich phase also suppresses brittle fracture. [ABSTRACT FROM AUTHOR]

Aluminum matrix nanocomposites (AMNCs) are a distinct category of advanced materials that incorporate nanoscale reinforcement in a ductile material matrix. Various nanomaterial reinforcements for AMNCs have been reported in the literature, including multi-walled carbon nanotubes (MWCNT), graphene nanoplatelets, silicon carbide, and boron nitride. These classes of materials have been described to exhibit both improvements and reductions in mechanical properties. The interfacial material phases result in low-strength materials. Improvements in mechanical properties are attributed by refined grain size and shape for both the matrix material and the reinforcement agent. These materials demonstrate higher hardness, yield strength, and wear corrosion compared to conventionally prepared aluminum composites. Spark plasma sintering (SPS) is one of the non-conventional sintering methods used to prepare metal matrix composites, resulting in fully dense composite materials. The SPS-produced metal matrix composite can be manufactured rapidly and finds its applications in the automotive, aerospace, and defense industries. This review provides an overview and current status of metal matrix composites regarding matrix and reinforcing materials and the SPS process for producing metal matrix composites. [ABSTRACT FROM AUTHOR]

This study focuses on understanding the impact of sequential ageing on the microstructural evolution of a large-grained structure homogenised cast alloy 625 and its effect on mechanical properties. SEM and TEM analyses of aged samples were conducted to comprehend various precipitation micromechanisms such as (i) nucleation and growth kinetics of γ′′ phase and (ii) transformation of primary carbides and grain boundary phase(s) evolved. The MC-based primary carbides are ascertained to transform into M23C6 secondary carbides following two completely different pathways: (I) MC + γ→ M23C6 + δ (mainly at grain boundary) and (II) MC + γ→M23C6 + γ″ (mainly within matrix). Furthermore, all three variants of γ″ phase are detected to evolve in the matrix displaying a crystallographic orientation of [001]γ″ // < 001>γ, and {100}γ″ // {100}γ. The formation of γ″ phase gradually improves the hardness of the material up to 650 h (224 HV) of ageing with a corresponding average precipitate size of 61 nm. The growth of γ″ particles complies with the Lifshitz–Slyozov–Wagner (LSW) theory of diffusion-controlled precipitate coarsening during the entire ageing period. Surprisingly, the hardness declined significantly beyond 650 h of ageing, even though the γ″ phase remained coherent with the matrix despite its coarsening (106 nm after 1000 h of ageing) and evidence of γ″→δ (mainly incoherent) transformation is not detectible throughout the ageing treatment. This lowering of hardness is attributed to a non-conventional slip-to-twin transition in the deformation mode of coherent γ″ particles after prolonged ageing, which is confirmed through tensile deformation micromechanisms analysis of the 650 and 1000 h aged samples. [ABSTRACT FROM AUTHOR]

β-type titanium alloys with a body-centered cubic structure are highly useful in orthopedics due to their low elastic modulus, lower than other commonly used alloys such as stainless steel and Co-Cr alloys. The formation of the β phase in titanium alloys is achieved through β-stabilizing elements such as Nb, Mo, and Ta. To produce new β alloys with a low modulus of elasticity, this work aimed to produce our alloy system for biomedical applications (Ti-50Nb-Mo). The alloys were produced by arc-melting and have the following compositions Ti-50Nb-xMo (x = 0, 3, 5, 7, and 12 wt% Mo). The alloys were characterized by density, X-ray diffraction, scanning electron microscopy, microhardness, and elastic modulus. It is worth highlighting that this new set of alloys of the Ti-50Nb-Mo system produced in this study is unprecedented; due to this, there needs to be a report in the literature on the production and structural characterization, hardness, and elastic modulus analyses. The microstructure of the alloys has an exclusively β phase (with bcc crystalline structure). The results show that adding molybdenum considerably increased the microhardness and decreased the elastic modulus, with values around 80 GPa, below the metallic materials used commercially for this type of application. From the produced alloys, Ti-50Nb-12Mo is highlighted due to its lower elastic modulus. [ABSTRACT FROM AUTHOR]

In this study, high entropy FeCoNiMnMoV and FeCoNiMn (Ferro Mo-Ferro-V) alloys were produced by arc melting method. After the arc melting process, the samples were annealed at 1000°C under argon atmosphere for 15 hours physical and thermodynamic calculations were performed to determine the properties of the alloy. In the study, both alloys were characterized. For characterization, XRD, SEM, EDS and Micro hardness were taken from the samples. The aim of my study is to examine the effect of using low-priced starting materials on the microstructure of HEA. For this purpose, ferro-alloys were added to the alloy. As a result, similar properties were obtained for the microstructure of both alloys. However, it has been determined that the hardness of samples containing ferro-alloys decreases more due to their chemical composition, especially after heat treatment. [ABSTRACT FROM AUTHOR]

Nanoindentation of ion-irradiated materials has attracted much interest as a tool envisaged to derive the dose dependence of bulk-equivalent hardness from small samples. A major challenge arises from the steep damage gradient in the thin ion-irradiated layer and its unavoidable interplay with the indentation size effect. The present study relies on a number of choices aimed at simplifying the interpretation of the results and strengthening the conclusions. The studied alloys are two ferritic Fe-9Cr model alloys differing in controlled amounts of Ni, Si, and P known to enhance irradiation hardening. Both ion-irradiated (5 MeV Fe2+ ions) and neutron-irradiated samples along with the unirradiated references were investigated using Berkovich tips. According to the collaborative nature of the study, tests were conducted in two different laboratories using different equipment. A generalized Nix–Gao approach was applied to derive the bulk-equivalent hardness and characteristic length scale parameters for the homogeneous unirradiated and neutron-irradiated samples. Comparison with Vickers hardness indicates a 6% overestimation of the bulk-equivalent hardness as compared to the ideal correlation. For the case of ion irradiation, a first model assumes a homogeneous irradiated layer on a homogeneous substrate, while a second model explicitly takes into account the damage gradient. The first model was combined with both the original and the generalized Nix–Gao relation. We have found that the results revealed for Fe-9Cr vs Fe-9Cr-NiSiP are compatible with expectations based upon known irradiation-induced microstructures. The bulk-equivalent hardness derived for ion-irradiated samples reasonably agrees with the observation for neutron-irradiated samples. [ABSTRACT FROM AUTHOR]

The impact of the heat treatments on the microstructure, high temperature hardness and wear performance at room and elevated temperature on a IN718 alloy fabricated via laser metal deposition (LMD) is investigated. It was found that the microhardness of the laser deposited IN718 alloy under different heat treatment conditions decreases with the increase of test temperature. Under various heat treatment conditions the wear rate of the laser deposited IN718 alloy at high temperatures is lower than that at room temperature. At room temperature the wear rate of the as-deposited IN718 alloy is higher than that of the heat treated samples. In contrast, at elevated temperatures the wear rate of the as-deposited IN718 alloy is lower than that of the heat treated samples. [ABSTRACT FROM AUTHOR]

Metallic diamond (MD) is a new alloy class which hardness was found to surpass any current alloys at more than a twofold factor, up to 2500 HV (kgf mm−2). The alloy design employs simple metallurgical principles at the so-called Lattice Occupancy Project aided by Diamoy 1.0 software. The most important aspect of the alloy project considers the maximization of chromium equivalent values by selecting metallic elements for promoting body-centred cubic structures. Forming these alloys into parts is challenging, whereas powder metallurgy techniques appear as valid processing routes. The work studies the sintering behaviour of MD-4 and 5 alloy powders, being the hardest MD ones. High energy milled powder compacts were sintered in a dilatometer up to 1500 °C for 1 h under Ar-10%H2 atmosphere. Alloy MD-5 has shown intense shrinkage starting at 1150 °C, contrasting to marginal sintering of alloy MD-4. The latter has undergone transformations from 400 °C with strong expansion, which seems to block most of the sintering retraction at higher temperatures. Alloy powder MD-5 is a good candidate as a raw material for tool parts production by powder metallurgy, which can compete with cemented carbide hard tools. [ABSTRACT FROM AUTHOR]

Searching for alternatives to diversification of production facilities that do not require significant material and energy costs is relevant in the face of pressing external factors. One of the promising technological fields of alloy production in metallurgy is the application of aluminothermic processes of remelting of thermite charge consisting of secondary materials (scale, chips of ferrous and nonferrous metals), used to produce a wide range of metal products without significant costs associated with the reequipment of production units. The possibility of controlling the parameters of alloys and properties of the final metal product formed by aluminothermic processes is implemented primarily by reducing the temperature of the metal phase of the melt by introducing inert fillers into the composition of mixtures, as well as holding the melt in the crucible before casting. The chemical composition, structure, and physical and mechanical properties of iron-carbon alloys are significant in forming several operational characteristics. The paper presents experiments aimed at studying the effect of the initial components of thermite charge materials used to produce iron-carbon alloys in aluminothermic processes, as well as the melt holding time in a crucible before casting on the chemical composition, microstructure, hardness, strength indicators, and the fracture characteristics. The focus of experimental investigations is on industrial applications in the metallurgical and machine-building sectors. [ABSTRACT FROM AUTHOR]

The characteristics of the modified layer of commercially pure BT1-0 titanium (c.p. BT1-0 titanium) after oxygen thermal diffusion saturation (oxidation) and subsequent electrospark alloying (ESA) with a graphite electrode were analyzed. The phase composition of surface layers, their hardness and tribological properties were studied. It was shown that both surface electrospark alloying of titanium with a graphite electrode and combined processing (oxidation followed by ESA) improve its tribological characteristics during friction without lubrication. As a result, the friction coefficient decreases from 0.4–0.5 to 0.15–0.17. At the same time, the wear resistance of titanium increases in 1.2–2.9 times. [ABSTRACT FROM AUTHOR]

Wire arc additive manufacturing (WAAM) was employed to fabricate 4043 aluminum alloy walls. To investigate the effects of sinusoidal, triangular, and rectangular waveforms of alternating current (AC) and their transients on the wall geometry, microstructure evolution, hardness, and wear properties were evaluated. The root mean square (RMS) current value was maximum for the rectangular and minimum for the triangular waveform. The section produced by the triangular waveform had the highest height-to-width ratio, indicating that this waveform can be a favorable choice for creating components using WAAM. The optical micrographs of the transverse cross-section of the printed sections revealed the grain structure produced with this waveform to be heterogeneous, having a columnar dendritic structure at the bottom and equiaxed at the top portion. The waveforms also had an impact on the hardness and wear characteristics of all the walls, which were attributed to their cooling rate. [ABSTRACT FROM AUTHOR]

Laser powder bed fusion (LPBF) is a metal additive manufacturing technology that is capable of printing metals and alloys with high quality. This study investigates wear characteristics of LPBF processed 316 L stainless steel and its correlation to the hardness and microstructure of the materials. The wear properties of LPBF specimen and hot rolled 316 L stainless steel were compared. From the analysis of wear characteristics of the samples, it was observed that the results were not consistent with the prediction of Archard's empirical equation. The LBPF processed samples with higher hardness exhibited lower wear resistance compared to the conventionally processed (hot rolled) samples. This study aimed at addressing such phenomenon by understanding the plasticity in those samples. Unconventional plastic deformation in LPBF 316 L samples with negligible work-hardening was observed which was believed to be the main reason for their lower wear resistance compared to conventionally processed samples. [ABSTRACT FROM AUTHOR]

A supersaturated Al-4.8%Zn-1.2%Mg-0.14%Zr (wt%) alloy was processed by the equal-channel angular pressing (ECAP) technique at room temperature in order to obtain an ultrafine-grained (UFG) microstructure having an average grain size of about 260 nm. The hardness and microstructural characteristics, such as the phase composition and precipitations of this UFG microstructure were studied using depth-sensing indentation (DSI), transmission electron microscopy (TEM), as well as non-isothermal scanning of differential scanning calorimetry (DSC), and compared to the properties of the un-deformed sample. Emphasis was placed on the effect of the UFG microstructure on the subsequent thermal processes in DSC measurements. It has been shown that the ECAP process resulted in not only an ultrafine-grained but also a strongly precipitated microstructure, leading to a hardness (2115 MPa) two and a half times higher than the initial hardness of the freshly quenched sample. Because of the significant changes in microstructure, ECAP has also a strong effect on the dissolution (endothermic) and precipitation (exothermic) processes during DSC measurements, where the dissolution and precipitation processes were quantitatively characterized by using experimentally determined specific enthalpies, ΔH and activation energies, Q. [ABSTRACT FROM AUTHOR]

Aluminium metal matrix composites (AMMCs) playing a prominent part in the aerospace and automotive sectors owing to their superior mechanical and tribological properties. Hence, the aim of this work is to investigate the effect of titanium dioxide (10 wt.% TiO2) particles addition on hardness and tribological behaviour of Al-0.6Fe-0.5Si alloy (AA8011) composite manufactured by stir casting method. The surface morphology of developed composite clearly shows the inclusion of TiO2 particles evenly distributed within the matrix alloy. Hardness of the composite was measured using Vickers micro hardness tester and the maximum hardness was obtained at 95.6 Hv. A pin-on-disc tribometer was used to carried the wear test under dry sliding conditions. The influence of wear control parameters such as applied load (L), sliding speed (S) and sliding distance (D) were taken as the input parameters and the output responses considered as the specific wear rate (SWR) and co-efficient of friction (COF). The experimental results were analyzed using Technique for Order Preference by Similarity to Ideal Preferred Solution (TOPSIS). Based on the TOPSIS approach, the less SWR and COF achieved at the optimal parametric combination were found to be L = 30 N, S = 1 m/s and D = 2000 m. ANOVA results revealed that applied load (76.01%) has the primary significant factor on SWR and COF, followed by sliding speed (20.71%) and sliding distance (3.12%) respectively. Worn surface morphology was studied using SEM image of confirmation experiment specimen to understand the wear mechanism [ABSTRACT FROM AUTHOR]

The recrystallization (RX) kinetics of commercially pure Al alloy is studied under the scope of annealing temperature, time, and degree of deformation. To examine the distribution of recrystallization, Johnson–Mehl–Avrami–Kolmogorov (JMAK) theory is employed, where the path of microstructural transformation from the deformed state to the fully recovered one is studied as a function of the volume fraction of recrystallized grains ( X V ) and annealing time. The drop in hardness is recorded for the samples at various stages of annealing with a corresponding decrease in stored energy as the annealing time increases. The stored energy obtained from the hardness results and Orientation Imaging Microscopy (OIM)-based method is found to be in good agreement with each other, proving the efficiency of both techniques. To determine the volume fraction of the recrystallized microstructure, data obtained from Vickers hardness measurements are used. Various parameters associated with recrystallization statistics such as the critical radius of nuclei, the incubation period, and the mobility of High-Angle Grain Boundaries (HAGB) were derived from the experimental evidence. The experimental data also suggest a sharp drop in the velocity of HAGB as the RX transformation process approaches its completion, which is found to be a direct result of a drop in stored energy. A softening window between 42 s and 55 s is identified for our experimental data where the hardness, stored energy, and velocity of HAGB drops very sharply, and the maximum fraction of deformed grains is expected to be converted to the recrystallized ones. Along with experimental observations, an analytical model was developed, which helps to approximate the kinetics of RX and corresponding parameters for various annealing temperatures and strains while revealing the characteristic feature of Avrami exponent n. Both experimental evidence and model data reveal a very strong dependency of recrystallization behavior on the stored energy. [ABSTRACT FROM AUTHOR]

The development of biodegradable Zn-based alloys for implants that effectively mimic the functionality of native bone throughout the healing process is a multifaceted challenge; this is particularly evident in the task of achieving appropriate corrosion rates. This work explores the incorporation of 0.5wt.%Mn into a Zn−1wt.%Mg alloy, with focus on the relationship between corrosion behavior and microstructure. Electrochemical corrosion tests were carried out in a 0.06 M NaCl solution using as-solidified samples with two distinct microstructural length scales. Mn addition was found to induce significant electrochemical active behavior. Localized corrosion was predominant in interdendritic regions, with the ternary alloy exhibiting a higher susceptibility. For both alloys, the coarsening of the microstructure promoted a slight inclination to accelerate the corrosion rates in both biodegradable Zn alloys. The corrosion rate showed an increase of about nine-times with Mn addition for coarser eutectic spacings, while for finer ones, the increase was by about 22 times. [ABSTRACT FROM AUTHOR]

Differences in the oxidation kinetics of zirconium and Zr–1% Nb alloy during heating in air depending on the heating rate, temperature and exposure time are revealed. The increase in the heating rate from 2.5 to 6 and 7.5°C/min reduces the activation energy of the Zr oxidation process in the temperature range of 20–1000°C from 70.2 to 67 and 52.7 kJ/mol, respectively. For the Zr–1% Nb zirconium alloy, increase in the heating rate from 5 to 10 and 20°C/min causes an increase in the activation energy of the oxidation process from 65 to 70.1 and 78.5 kJ/mol, respectively. Such an increase in the heating rate (of zirconium from 2.5 to 7.5°C/min, and of the Zr–1% Nb alloy from 5 to 20°C/min) causes a decrease in the thickness of the ZrO2 oxide film. During isothermal exposure for 5 h at 750°C, Zr–1% Nb alloy and Zr at a temperature of 800°C are oxidized according to the parabolic law. At 800°C Zr–1% Nb alloy oxidizes according to the combined law: first, parabolic, and then quasi-linear. [ABSTRACT FROM AUTHOR]

The influence of electron concentration, mixing enthalpy, and dimensional mismatch on the lattice parameter, elastic modulus, and normalized hardness of fcc high-entropy alloys (HEA) is studied. The lattice parameter, which determines the elastic modulus of HEA, is influenced by both the electron concentration and the mixing enthalpy. A rectilinear dependence of the normalized hardness of these alloys on the dimensional discrepancy is established. Formulas for calculating the hardness and the elastic modulus for hard-soluble HEA with fcc lattice are proposed. [ABSTRACT FROM AUTHOR]

Most metals and alloys suffer from high friction and wear due to their low hardness and lack of self‐lubrication. Although plenty of strategies have been proposed, it is still a long‐standing challenge to achieve diamond‐like wear in metals. Metallic glasses (MGs) are supposed to possess low coefficient of friction (COF) because of their high hardness and fast surface mobility. However, their wear rate is larger than that of diamond‐like materials. Here, this work reports the discovery of Ta‐rich MGs that exhibit diamond‐like wear. This work develops an indentation approach for high‐throughput characterization of crack resistance. By employing deep indentation loading, this work is able to efficiently identify the alloys that exhibit better plasticity and crack resistance according to the differences of indent morphology. With high temperature stability, high hardness, improved plasticity, and crack resistance, the discovered Ta‐based MGs exhibit diamond‐like tribological properties, featured by COF as low as ≈0.05 for diamond ball test and ≈0.15 for steel ball test, and specific wear rate of only ≈10−7 mm3 N−1m−1. The discovery approach and the discovered MGs exemplifie the promise to substantially reduce friction and wear of metals and may unleash the potential of MGs in tribological applications. [ABSTRACT FROM AUTHOR]

In this study, the effects of casting modifiers on the surface roughness and chip formation of Al-12Si alloy materials were experimentally investigated. Machinability tests were carried out using a conventional lathe. Machinability tests were performed on four different materials, Etial 140, Etial 140 +CuSn5, Etial 140 +Al10Sr and Etial 140 +Al10Sr+CuSn5, respectively. A constant depth of cut, 3 different cutting speeds (Vc: 35, 95, 135 m/min) and three different feed rates (f: 0.08, 0.16, and 0.32 mm/rev) were chosen as test parameters. The most effective roughness reduction under these test conditions was 7.21% for the Al10Sr modified test material. According to the measured density values of the unmodified material, the density values of the other tested materials increased by 1.65% for CuSn5, 0.40% for Al10Sr and 1.16% for CuSn5+Al10Sr. Furthermore, the hardness values increased by 5.48% for CuSn5, 0.58% for Al10Sr, and 15.75% for CuSn5+Al10Sr. [ABSTRACT FROM AUTHOR]

In this paper, the high strength and lightweight Al–Cu–Li alloy (AA2099) is considered in as-built and preheated conditions (440 °C, 460 °C, 480 °C, 500 °C, and 520 °C). The purpose of this study is to investigate the influence of laser powder bed fusion (LPBF) in situ preheating on precipitation microstructure, mechanical and corrosive properties of LPBF-printed AA2099 alloy compared to the conventionally processed and heat-treated (T83) alloy. It is shown that precipitations evolve with increasing preheating temperatures from predominantly globular Cu-rich phases at lower temperatures (as-built, 440 °C) to more plate and rod-like precipitates (460 °C, 480 °C, 500 °C and 520 °C). Attendant increase with increasing preheating temperatures are the amount of low melting Cu-rich phases and precipitation-free zones (PFZ). Hardness of preheated LPBF samples peaks at 480 °C (93.6 HV0.1), and declines afterwards, although inferior to the T83 alloy (168.6 HV0.1). Preheated sample (500 °C) shows superior elongation (14.1%) compared to the T83 (11.3%) but falls short in tensile and yield strength properties. Potentiodynamic polarization results also show that increasing preheating temperature increases the corrosion current density (Icorr) and corrosion rate. Indicated by the lower oxide resistance (Rox), the Cu-rich phases compromise the integrity of the oxide layer. [ABSTRACT FROM AUTHOR]

In this paper, we study the effect of deposition temperature on the structural and nanomechanical properties on the degradation and bioactivity behaviour of Mg doped hydroxyapatite (HAP) deposited on AZ31B alloy substrates extracted by parts manufactured according to the prostheses production route. The coatings were prepared by RF (Radio Frequency) magnetron sputtering technique at room temperature (RT) and 200 °C, respectively. By adding Mg into the HAP matrix, the hardness and elastic modulus values of the coatings have significantly improved as compared to the bare HAP, the highest H3/E2 ratio of 0.022 being obtained for the HAP + Mg at 200 °C. XRD analysis showed the presence of an α-Mg hexagonal structure for the uncoated AZ31B alloy, while the GIXRD patterns revealed the presence of HAP and Mg in the coated samples. The crystallinity degree of HAP is not changed by Mg addition, while the apatite structure was preserved for all investigated coatings. All investigated samples exhibited typical IR bands of phosphate, carbonate, and hydroxyl functional groups, confirming the formation of apatite phases. By increasing the deposition temperature from room temperature up to 200 °C, the electrochemical behaviour of the coatings, in simulated body fluid and Dulbecco's Modified Eagle Medium, is improved obtaining more electropositive values for corrosion potential, smaller current densities, and higher polarization resistance. The coatings deposited at 200 °C showed the best electrochemical behaviour. Also, by increasing the deposition temperature and incorporating Mg into HAP matrix, the hardness and elastic modulus are increased by more than two-fold, as compared to pure HAP. Furthermore, all coatings deposited on AZ31B alloys are suited for further coating with a mussel-derived surface-binding peptides, but the coatings deposited at 200 °C led to the most regular peptide distribution on the surface. Overall, the results indicated that the biodegradation of HAP + Mg based coatings and the AZ31B alloys can be controlled according to the current clinical needs within implantology field. [ABSTRACT FROM AUTHOR]

The article presents research on the metallurgical synthesis of the CuNiSi alloy with a nickel content of 2,2 wt.% and silicon in the range of 0,8 - 1,3 wt.%. Each of the produced materials were subjected to the process of homogenization, solution heat treatment and artificial aging in order to improve the mechanical and electrical properties. Materials were directed to the chemical composition tests, Vickers hardness and electrical conductivity tests and also for microstructural tests with using scanning electron microscopy (SEM). [ABSTRACT FROM AUTHOR]

The aluminum alloy are extensively used in several industrial applications. Stir casting is one of the most frequently accepted methods. In the present investigation, how the microstructure, mechanical and wear mechanics of A357 alloy were impacted by the presence of Sr/Ca was investigated. The outcomes revealed that addition of elements (Sr/Ca) enhance the microstructural features. Uniform dispersal of particulates (Sr/ Ca) in Al357 alloy and also the modified structure of silicon (Si) were observed. Hardness of modified alloy was evaluated by using hardness tester. A result reveals that hardness of modified alloy was improved by increasing in the Sr/Ca content. The wear rate of modified alloy was evaluated by using Pin and Disc wear test rig. Test trials were conducted according to Taguchi technique. L27 array was implemented for evaluation of data. The effect of varying parameters (factors) on wear loss and COF were analyzed using ANOVA (Analysis of Variance) method. ANOVA outcomes shown that, the Sr/Ca content has a better significant impact on wear behavior and COF of the modified alloy. A wear fractography result shows the internal fracture structure of a wornout surface which was studied by SEM analysis. [ABSTRACT FROM AUTHOR]

In this study, Al7075+0%Ti-, Al7075+2%Ti-, Al7075+4%Ti-, and Al7075+8%Ti-reinforced alloys were prepared by melting processes using Al7075 and Al-10%Ti main alloys. All newly produced alloys were subjected to T6 aging heat treatment and some samples were cold rolled at 5% beforehand. The microstructure, mechanical behavior, and dry-wear behavior of the new alloys were examined. Dry-wear tests of all alloys were carried out at a total sliding distance of 1000 m, at a sliding speed of 0.1 m/s, and under a load of 20 N. In the hardness measured after T6 aging heat treatment, the peak hardness of the Al7075+0%Ti-, Al7075+2%Ti-, Al7075+4%Ti-, and Al7075+8%Ti-reinforced alloys was found to be 105.63, 113.60, 122.44, and 140.41 HB, respectively. The secondary phases formed by the addition of Ti to the Al7075 alloy acted as precipitate-nucleation sites during aging heat treatment, further increasing the peak hardness. Compared to the peak hardness of the unrolled Al7075+0%Ti alloy, the increase in the peak hardness of the unrolled and rolled Al7075+8%Ti-reinforced alloys was 34% and 47%, respectively, and this difference in the increase was due to the change in the dislocation density with cold deformation. According to the dry-wear test results, the wear resistance of the Al7075 alloy increased by 108.5% with a reinforcement of 8% Ti. This result can be attributed to the formation of Al, Mg, and Ti-based oxide films during wear, as well as the precipitation hardening, the secondary hardening with acicular and spherical Al3Ti phases, the grain refinement, and solid-solution-hardening mechanisms. [ABSTRACT FROM AUTHOR]

We investigate by molecular dynamics simulation the mechanical behavior of concentrated alloys under nanoindentation for the special example of single-phase fcc Fe x Ni 1 - x alloys. The indentation hardness is maximum for the equiatomic alloy, x = 0.5 . This finding is in agreement with experimental results on the strength of these alloys under uniaxial strain. We explain this finding with the increase of the unstable stacking fault energy in the alloys towards x = 0.5 . With increasing Fe content, loop emission from the plastic zone under the indenter becomes less pronounced and the plastic zone features a larger fraction of screw dislocation segments; simultaneously, the length of the dislocation network and the number of atoms in the stacking faults generated in the plastic zone increase. However, the volume of twinned regions in the plastic zone is highest for the elemental solids and decreases for the alloys. This feature is explained by the fact that twinning proceeds by the glide of dislocations on adjacent parallel lattice planes; this concerted motion is less efficient in the alloys. Finally, we find that surface imprints show increasing pile-up heights with increasing Fe content. The present results will be of interest for hardness engineering or generating hardness profiles in concentrated alloys. [ABSTRACT FROM AUTHOR]

This paper presents simulation results of the ionization losses of incident He2+ ions with an energy of 40 keV during the passage of incident ions in the near-surface layer of alloys based on TiTaNbV with a variation of alloy components. For comparison, data on the ionization losses of incident He2+ ions in pure niobium, followed by the addition of vanadium, tantalum, and titanium to the alloy in equal stoichiometric proportions, are presented. With the use of indentation methods, the dependences of the change in the strength properties of the near-surface layer of alloys were determined. It was established that the addition of Ti to the composition of the alloy leads to an increase in resistance to crack resistance under high-dose irradiation, as well as a decrease in the degree of swelling of the near-surface layer. During tests on the thermal stability of irradiated samples, it was found that swelling and degradation of the near-surface layer of pure niobium affects the rate of oxidation and subsequent degradation, while for high-entropy alloys, an increase in the number of alloy components leads to an increase in resistance to destruction. [ABSTRACT FROM AUTHOR]

The tribological characteristics of stir cast Al-15%Si-10%Zn matrix with 15%ZrO2 reinforced composite were investigated. The microstructure of the Al-15Si alloy consisted of coarse primary Si and acicular eutectic Si phases randomly distributed in the Al dendrites. The Al-15%Si-10%Zn/ZrO2 composite showed spherical Si with a size between 25 and 75 µm; fragmented eutectic Si phase and uniform dispersion of ZrO2 particles in the matrix. The wear test was conducted using in a pin-on-disc method at different loads and sliding velocities. It was found reduced coefficient of friction, significant increase in the hardness and wear resistance of the composite compared to the matrix alloy. High wear resistance in the composite due to the effect of solid lubrication provided by Zn, and good fracture toughness and wear resistance by the reinforced ZrO2 particles. The predominant oxidative and abrasive wear were identified as the mechanisms leading to material failure through plastic deformation and delamination. [ABSTRACT FROM AUTHOR]

AA6101 Al alloy is widely used as a high-strength conductive aluminum alloy, and the contents and existence of Mg and Si can influence its electrical conductivity and mechanical properties obviously. In this paper, experiments were conducted to find the optimal Mg, Si additions and Mg/Si ratio and then combined with heat treatment to improve the EC and mechanical properties at the same time. Firstly, considering the proper Mg/Si ratio, two optimal Mg and Si additions were determined: Al–0.7Mg–0.5Si and Al–0.4Mg–0.7Si with EC of 51.5%IACS and 51.4%IACS, and through homogenization treatment, their EC improved to 57.0%IACS and 55.7%IACS, respectively. Then, appropriate Fe was added to further control Si to achieve the balance of EC and mechanical properties. Results showed that for AA6101 Al alloy the ideal Mg/Si mass ratio was 1.4 and high Mg and low Si can obtain good EC and mechanical properties. Besides, it can be found that at low Mg/Si ratio, the alloy conductivity takes longer to reach its peak hardness. So the best performance Al–0.7Mg–0.5Si–0.2Fe alloy was obtained within the range of AA6101 national standard. The EC of Al–0.7Mg–0.5Si–0.2Fe can reach 56.3%IACS, and hardness is 91.3 Hv. Based on the study, a schematic diagram was drawn to analyze the influence mechanisms of Mg, Si and Fe on EC and hardness of AA6101 Al alloy. [ABSTRACT FROM AUTHOR]

The fineness and hardness of "5G gold" jewelry were tested by fire assay, ICP difference method, and microscopic hardness tester. The results show that the fineness of "5G gold" jewelry on the market meets the requirements of GB 11887-2012 Jewelry-Fineness of Precious Metal Alloys and Designation; the minimum hardness of the tested "5G gold" jewelry is 29.2 HV, and the maximum is 120.7 HV. The hardness value of most samples is in the range of 50-80 HV. The hardness of "5G gold" jewelry is mainly improved through microalloying, cold deformation, surface electroforming, and other methods, involving solid solution strengthening, precipitation strengthening, deformation strengthening, and fine-grain strengthening mechanisms. [ABSTRACT FROM AUTHOR]

The effect of final thermomechanical treatment (FTMT) on the mechanical properties and microstructure of a T-Mg32(Al Zn)49 phase precipitation hardened Al-5.8Mg-4.5Zn-0.5Cu alloy was studied. The as-cold rolled aluminum alloy samples were subjected sequentially to solid solution treatment, pre-deformation, and two-stage aging treatment. Vickers hardness was measured during the aging process under various parameters. Tensile tests were conducted on the representative samples based on the hardness results. Microstructural characteristics were analyzed via transmission electron microscopy and high-resolution transmission electron microscopy. The conventional T6 process was also carried out for comparison. The hardness and tensile strength are increased evidently by the FTMT process for the Al-Mg-Zn-Cu alloy, while the ductility is adversely affected to a small extent. The precipitation at the T6 state consists of a coherent Guinier–Preston zone and T″ phase in the form of intragranular, fine, and spherical particles, while a semi-coherent T′ phase appears after the FTMT process as a new constituent. The distribution of dislocation tangles and isolated dislocations is another feature of FTMT samples. Enhanced precipitation hardening and dislocation strengthening account for the improved mechanical performance of FTMT samples. [ABSTRACT FROM AUTHOR]

The present work was performed on experimental Al-Si near eutectic cast alloys, with different additives, mainly Fe, Mg, Mn, Cr, Sr and P. The alloys were solidified at 0.8°C/s, very close to equilibrium conditions. Precipitated phases, primarily Fe-, Cu-, Mg-, and Sr-based intermetallics, were examined. Although the phases reported in the present work were documented previously, the range of chemical composition of each phase was confirmed using an electron probe microanalyzer (EPMA) equipped with wavelength dispersive spectroscopy (WDS) and electron dispersive X-ray spectroscopy (EDS) facilities. Some of these alloys were cast to produce hardness test samples using a metallic permanent mold preheated at 425 °C that provided a microstructure with an average dendrite arm spacing (DAS) of ~22 µm. Samples were solution heat treated at 495 °C ± 2 °C for times up to 24 h, followed by quenching in warm water (65 °C), and thereafter artificial aging at 155 °C for 5 h (T6 treatment). Hardness and impact tests were carried out on the heat-treated test bars. [ABSTRACT FROM AUTHOR]

This work deals with the characterization of structure, magnetic and mechanical properties of (FeNiCo)100-x(AlSi)x (x = 0, 5, 10, 15, 25) multicomponent alloys prepared by casting. The results of X-ray diffraction measurements, scanning electron microscopy observations and hardness and magnetic properties investigations are presented. The studies show that cast (FeNiCo)100-x(AlSi)x alloys reveal dendritic morphology and their phase composition depends on (Al + Si) content. For x = 10 a face-centered cubic phase is observed, while the increase of Al and Si content results in a body-centered cubic phase formation. It leads to a fivefold increase of hardness from 88 HV to 526 HV. The investigated alloys have high magnetic induction reaching 170 emu/g, while their coercivity value is even up to 2.9 kA/m for x = 15, and strongly depends on chemical and phase composition. [ABSTRACT FROM AUTHOR]

This paper is devoted to the evaluation of the "three-body-abrasion" wear behaviour of (wt.%) 5W–5Mo–5V–10Cr-2.5Ti-Fe (balance) multi-component (C + B)-added alloys in the as-cast condition. The carbon (0.3 wt.%, 0.7 wt.%, 1.1 wt.%) and boron (1.5 wt.%, 2.5 wt.%, 3.5 wt.%) contents were selected using a full factorial (32) design method. The alloys had a near-eutectic (at 1.5 wt.% B) or hyper-eutectic (at 2.5–3.5 wt.% B) structure. The structural micro-constituents were (in different combinations): (a) (W, Mo, and V)-rich borocarbide M2(B,C)5 as the coarse primary prismatoids or as the fibres of a "Chinese-script" eutectic, (b) Ti-rich carboboride M(C,B) with a dispersed equiaxed shape, (c) Cr-rich carboboride M7(C,B)3 as the plates of a "rosette"-like eutectic, and (d) Fe-rich boroncementite (M3(C,B)) as the plates of "coarse-net" and ledeburite eutectics. The metallic matrix was ferrite (at 0.3–1.1 wt.% C and 1.5 wt.% B) and "ferrite + pearlite" or martensite (at 0.7–1.1 wt.% C and 2.5–3.5 wt.% B). The bulk hardness varied from 29 HRC (0.3 wt.% C–1.5 wt.% B) to 53.5 HRC (1.1 wt.% C–3.5 wt.% B). The wear test results were mathematically processed and the regression equation of the wear rate as a function of the carbon and boron contents was derived and analysed. At any carbon content, the lowest wear rate was attributed to the alloy with 1.5 wt.% B. Adding 2.5 wt.% B led to an increase in the wear rate because of the appearance of coarse primary borocarbides (M2(B,C)5), which were prone to chipping and spalling-off under abrasion. At a higher boron content (3.5 wt.%), the wear rate decreased due to the increase in the volume fraction of the eutectic carboborides. The optimal chemical composition was found to be 1.1 wt.% C–1.5 wt.% B with a near-eutectic structure with about 35 vol.% of hard inclusions (M2(B,C)5, M(C,B), M3(C,B), and M7(C,B)3) in total. The effect of carbon and boron on the abrasive behaviour of the multi-component cast alloys with respect to the alloys' structure is discussed, and the mechanism of wear for these alloys is proposed. [ABSTRACT FROM AUTHOR]

Additive manufacturing (AM) of Ni-based super alloys is more challenging, compared to the production other metallic alloys. This is due to their high melting point and excellent high temperature resistance. In the present work, an Inconel 718 alloy was fabricated by a powder laser bed fusion (P-LBF) process and investigated to assess its microstructural evolution, together with mechanical properties. Additionally, the alloy was compared against the cast (and forged) alloy of similar composition. The microstructure of the P-LBF-processed alloy shows hierarchy microstructure that consists of cellular sub-structure (~100–600 nm), together with melt pool and grain boundaries, in contrast of the twin infested larger grain microstructure of the cast alloy. However, the effect of such unique microstructure on mechanical properties of the L-PBF alloy was overwritten, due to the absence of precipitates. The hardness of the L-PBF-processed alloy (330–349 MPa) was lower than that of cast alloy (408 MPa). The similar trend was also observed in other mechanical properties, such as Young's modulus, resistance to plasticity and shear stress. [ABSTRACT FROM AUTHOR]

We investigated the aging behaviour of a Mg-10Gd-3Y-1.0Zn-0.5Zr (wt.%) alloy with long-period stacking ordered (LPSO) phase at 275°C. Its peak hardness is about 116.4 HV after aging for 25 h. We unravelled the evolution of prismatic precipitates through transmission electron microscopy (TEM). The formation process is β′ (10h)→ β′ + β1 (15 h)→ β′ + β1 + β (≥20 h), where nano-scale β ′ F phase benefits the transformation from β′ phase to β1 phase. In addition to the stable basal LPSO structures, the coexistence and competition balance between the prismatic β′, β1 and β phases synergistically contribute to the high hardness of the aged alloy. The number density of the prismatic precipitates is at the magnitude of 1020/m3. These prismatic precipitates during aging largely determine the hardness of the Mg alloys. The interaction between precipitates and stacking faults brings good compression property. [ABSTRACT FROM AUTHOR]