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To overcome the limitation in formability at room temperature, manufacturers have developed magnesium alloys with remarkable properties by adding rare-earth elements. The rare-earth magnesium alloys behave differently from the conventional alloys, especially with respect to their coupled anisotropic and strain rate sensitive behavior. In the current work, such behavior of the rare-earth Mg alloy ZEK100 sheet at room temperature is investigated with the aid of the elastic viscoplastic self-consistent polycrystal plasticity model. Different strain rate sensitivities (SRSs) for various deformation modes are employed by the model to simulate the strain rate sensitive behaviors under different loading directions and loading rates. Good agreement between the experiments and simulations reveals the importance and necessity of using different SRSs for each deformation mode in hexagonal close-packed metals. Furthermore, the relative activities of each deformation mode and the texture evolution during different loadings are discussed. The anisotropic and strain rate sensitive behavior is ascribed to the various operating deformation modes with different SRSs during loading along different directions. [ABSTRACT FROM AUTHOR]

AlCrFeNi medium-entropy alloy (MEA) without expensive Co has demonstrated superior properties over the well-known AlCoCrFeNi high-entropy alloy. We added NbC particles to the MEA to make NbC-reinforced MEA alloys or MEA-matrix composites, and evaluated their wear resistances and mechanical properties. The materials showed considerably improved performance. To well judge the NbC-MEA for realistic applications, the wear resistance of the NbC-MEA samples was compared with those of a few industrial wear-resistant materials, e.g., high-Cr cast iron (HCCI) and WC-Co composites. It was demonstrated that the MEA samples with 40–60 vol% NbC exhibited markedly higher wear resistance than the reference materials, and the MEA demonstrated high superiority over the widely used Co as the metal-matrix for developing wear-resistant metal-matrix composites (MMCs). [ABSTRACT FROM AUTHOR]

Here, an Fe 85.7 Si 1 B 10 C 1 P 2 Cu 0.3 diluted nanocrystalline alloy exhibiting relatively high B s of 1.69 T and low H c of 2.58 A/m is successfully developed. In addition, the effects of substituting C with P on the thermal behavior, magnetic properties, microstructure, and magnetic domains of Fe 85.7 Si 1 B 10 C 3−x P x Cu 0.3 (x = 0, 1, 2, and 3 at%) amorphous alloys are investigated. It is found that the addition of P not only improves glass forming ability, but also enhances thermal stability of the amorphous alloy. Furthermore, the suitable P addition can also optimize the soft magnetic properties under heat treatment. For the Fe 85.7 Si 1 B 10 C 1 P 2 Cu 0.3 alloy, the improved B s is due to the formation of bcc -Fe crystals and the lowest H c is caused by the low magneto-crystalline anisotropy, which are both induced by the construction diluted nanocrystalline structure. The formation of this unique microstructure is due to the competition between stabilization effect on amorphous phase of higher crystallization activation energy and the facilitation effect on the formation of bcc -Fe crystal by atomic-scale preexisting crystal-like clusters. • A novel Fe 85.7 Si 1 B 10 C 1 P 2 Cu 0.3 diluted nanocrystalline alloy exhibiting high B s of 1.69 T and low H c of 2.58 A/m is developed. • The suitable P addition can optimize the soft magnetic properties (SMPs) in FeSiBCCu nanocrystalline alloy system. • The competition between crystallization activation energy and the formation of bcc -Fe crystal leads to the excellent SMPs. [ABSTRACT FROM AUTHOR]

Surface nanocrystallization is beneficial to the corrosion resistance of passive alloys, but generally has a negative effect on the corrosion behavior of non-passive alloys due to the enhanced surface reactivity. In this study, a combination of Al diffusion treatment and surface nanocrystallization was applied to carbon steel with the aim of exploring an alternative approach to improve the corrosion resistance of non-passive carbon steel. The surface nanocrystallization was achieved by sandblasting and subsequent recovery treatment. The former resulted in severe plastic deformation, while the latter turned high-density dislocation cells into nano-sized grains. The present study demonstrates that the combined Al diffusion and nanocrystallization generated a nanocrystalline Al-containing surface layer on the carbon steel with its surface grain diameter in the range of 10-300 nm. The corrosion resistance of the treated steel was evaluated. It is demonstrated that treated specimens possess increased resistance to corrosion with higher surface electron stability. Surface microstructure of the treated specimens was examined using SEM, AFM, and EDS in order to elucidate the mechanism responsible for the improved corrosion resistance. [ABSTRACT FROM AUTHOR]

Abstract: Cobalt-based alloys are often used for bearing applications, especially at elevated temperatures. One of the newly developed 700 series cobalt-based alloys, Stellite 712, has been demonstrated to possess high resistance to wear and corrosion in aggressive environments. Continuous efforts have been made to further improve this alloy for enhanced resistance to high-temperature wear involving oxidation. Recent studies showed that the improvement of the oxide scale on Co-base alloys by alloying with yttrium was an effective way to diminish wear of the alloys at elevated temperatures. In this work, sliding wear performances of yttrium-free and yttrium-containing Stellite 712 samples at elevated temperatures were evaluated. The mechanism responsible for changes in its wear performance was investigated by studying the effects of alloying yttrium on microstructure and mechanical properties of the bulk alloy and its oxide scale, employing various experimental methods including micro- and nano-mechanical probing, XRD, SEM-EDS, AFM and high-temperature pin-on-disc wear testing. The research demonstrated that alloying a small amount of yttrium (e.g. less than 1%Y) rendered the oxide scale on Stellite 712 stronger with higher adherence to the substrate, which was largely beneficial to the wear performance of the alloy at elevated temperatures. Mechanisms involved are discussed in this article. [Copyright &y& Elsevier]

A micro-scale dynamic model was extended to simulate erosion–corrosion proceses. In this model, a material system is discretized and mapped onto a discrete lattice. Each lattice site represents a small volume of the target material or of a solid particle. During solid-particle erosion in a corrosive solution, a lattice site may move under the influence of impingement between an ejected solid particle and the target material as well as the interaction between the site and its adjacent sites. The lattice site and bonds connecting this site to its neighbors dissolve if they are exposed to the corrosive solution. The site–site interaction is a function of mechanical properties of the material, including elastic modulus, yield strength, work hardening, fracture strain, and the dissolution rate of the material in the corrosive solution. The dissolution rate is influenced by deformation of the target material. A site or a cluster of sites can be worn away if all bonds connecting the site or the cluster to its adjacent sites are broken. A site may also be destroyed if it completely dissolves in the solution. In this study, erosion–corrosion of 1045 carbon steel in a HCl solution was modeled, in which no passivation was involved. Relevant experiments were performed. Consistence between the modeling and experimental observation has been found. [Copyright &y& Elsevier]

Effects of alloying yttrium on the wear behavior of a commercial wear-resistant alloy, Stellite 6, at elevated temperatures were investigated. Samples of Stellite 6 alloyed with various amounts of yttrium were made using an arc-melting furnace. Structure of the modified Stellite 6 was analyzed using the X-ray diffraction technique (XRD). The wear behavior of the samples at various temperatures from the room temperature up to 650 °C was evaluated using a high temperature pin-on-disc tribometer. It was demonstrated that the alloyed yttrium considerably improved the alloy with improved wear resistance and mechanical behavior. In order to better understand the effect of yttrium on high-temperature wear behavior of the alloy, the structure and mechanical properties of oxide scales developed on Y-containing and Y-free samples were investigated, respectively, employing the grazing incidence XRD and nano-indentation techniques. The resistance of the oxide scales to scratch failure was also investigated using a micro-scratcher with in situ monitoring changes in the contact electrical resistance. It was demonstrated that the oxide scale was considerably enhanced when yttrium was added to the alloy, which could contribute to the improved performance of the alloy at elevated temperatures. [Copyright &y& Elsevier]

High-entropy alloys (HEAs) are generally in a solid-solution state, possessing some superior properties over conventional alloys due to their microstructural homogeneity, effective multi-element strengthening and deformation twinning. In the present study, 10 at% Ti was added to an equiatomic AlCoCrFeNi high-entropy alloy, which increased its microstructural inhomogeneity with the formation of distinctive honeycomb-shaped interdendrites. The performances of the AlCoCrFeNi alloy and the Ti-added one, AlCoCrFeNiTi 0.5 , during unidirectional and bi-directional sliding wear processes were investigated. It was shown that the addition of Ti considerably enhanced the HEA against wear under both the sliding conditions mainly due to the increased hardness. The volume loss decreased during bi-directional sliding, which was further decreased as the sliding direction was reversed more frequently. The decreased wear by bi-directional sliding was attributed to the Bauschinger effect in which defect annihilation (i.e., cancellation of dislocations of opposite signs) occurred with reversal of the wearing stress. The Ti addition did not show much influence on the trend of wear variations with the wearing stress reversal except the magnitude of material loss. By performing wear tests with and without air-flow cooling, it was shown that local heating by friction promoted the Bauschinger effect, which could be ascribed to the increase in the dislocation mobility and reversibility at elevated temperatures. • AlCoCrFeNi high-entropy alloy consists of disordered BCC and ordered BCC-B2 domains. • Adding Ti to AlCoCrFeNi forms honeycomb-shaped interdendrite and the intertwined structure. • The Ti addition enhances the wear resistance of AlCoCrFeNi due to increased hardness and the protective oxide scale on surface. • Bi-directional sliding causes less wear, which is attributed to the Bauschinger effect involving annihilation of dislocations. • Frictional heating facilitates the Bauschinger effect, due to the increases in dislocations' mobility and annihilation. [ABSTRACT FROM AUTHOR]

Attributed to their superior properties over the conventional alloys, high-entropy alloys (HEAs) have attracted considerable interest. One of HEAs' attractive properties is their high wear resistance. Although considerable research on wear of HEAs can be found in the literature, understanding of the responses of HEAs to different wearing conditions needs to be enhanced in order to utilize HEAs effectively. For instance, studies on nano-wear and nano/micro-machining under different conditions are rare, which influences the extension of HEAs' applications to nanotechnological areas, e.g., nano/micro-devices and nano-manufacturing. In this study, we conducted molecular dynamics simulations to investigate responses of CrMnFeCoNi and CrFeCoNi HEAs to wear under unidirectional and bi-directional sliding conditions, respectively, for two nano-wearing processes. One process is similar to nano-machining and the other is sliding wear on nano-scale under a light normal force. Due to its higher hardness, the Mn-free HEA is more resistant to wear than the Mn-containing one. During the simulated nano-machining process, both the alloys were worn more under the bi-directional sliding condition. While the situation was reversed during the sliding wear process, in which the bi-directional sliding caused less wear. Bauschinger's effect plays a role in influencing the wear behavior of the HEAs under the different conditions. This work provides an insight into nano-tribological behaviors of the alloys under different wearing conditions, helping either mitigate wear of HEAs or improve their machining efficiency. • Nano-tribological behaviors of high-entropy alloys, CrMnFeCoNi and CrFeCoNi, are investigated. • CrFeCoNi is more wear resistant than CrMnFeCoNi due to its higher hardness. • The HEAs were worn more under the bi-directional sliding condition during the nano-machining process. • HEAs were worn less under the bi-directional sliding condition during the sliding wear process. • Bauschinger's effect plays a role in influencing the wear behavior of the HEAs. [ABSTRACT FROM AUTHOR]

CoCrFeMnNi high entropy alloy films (HEAFs) with different thicknesses (250 to 1400 nm) and structures were fabricated by magnetron sputtering to study the relation among the wettability, surface electron activity and corrosion resistance of the films. The XRD pattern showed the transition from the amorphous phase to face-centered cubic (FCC) structure with the increasing film thickness. The SEM micrographs of film surfaces showed changes from the morphology consisting of sphere-like islands to ligament-like islands with the increasing film thickness. The surface wettability, electron work function (EWF) and corrosion resistance of the CoCrFeMnNi HEAFs were studied using contact angle measurements, scanning Kelvin probe and electrochemical system, respectively. The film surface with the higher EWF is more stable with a higher degree of inertness, ascribed to its less active surface electrons, leading to the lower surface activity which contributes to the lower polarity, higher hydrophobicity and corrosion resistance. The 550 nm-thick film with the smallest grain size at the nano-scale and the highest density of grain boundaries showed the highest EWF (4.2 eV), the greatest hydrophobicity (96° water contact angle) and the outstanding corrosion resistance (E corr = −301 mV and I corr = 0.481 μA/cm2). Unlabelled Image • We deposited high entropy alloy films with different thicknesses and structures. • Transition from amorphous to nanocrystalline with increasing film thickness was observed. • We correlated the wettability, electron work function (EWF) and corrosion of films. • The film surface with the higher EWF is more hydrophobic and corrosion resistant. • The film with the smallest nanosized grain showed the highest EWF. [ABSTRACT FROM AUTHOR]

Surface severe plastic deformation (SPD) is an approach used to nanocrystallize metallic surfaces for enhanced resistance to wear. However, SPD alone does not generate well-defined nanocrystalline structure but one consisting of nano-sized dislocation cells with diffuse boundaries. For materials with limited slip systems such as Mg, SPD may harden the materials but deteriorate their fracture toughness. As a result, the benefit of SPD to the wear resistance of materials may not be appreciable. In this study, we nanocrystallized the surface layer of AZ31 Mg alloy by repeated hammering, followed by recovery treatment (HR). The microstructure, wear behavior, grain structure and wear debris of differently treated samples, including hammering (HM), hammering plus recovery treatment (HM-R), and as-received, were investigated and compared. Results of the study show that the SPD-HR sample had a superior nanocrystalline surface exhibiting the highest wear resistance. The hammered sample (HM) was harder than the HM-HR one but its wear resistance is lower than that of the latter, though it still performed better than the as-received one. The wear debris analysis showed that the surface of the HM-R sample was tougher than that of the HM one. The observed phenomena indicate that the wear resistance of AZ31 Mg alloys depends on both hardness and toughness to which the ductility is of importance. The recovery treatment after HM certainly helped achieving well-defined nanocrystallization for improved wear resistance of the Mg alloy. • Surface nanocrystallization of AZ31 Mg alloy by hammering and recovery treatment considerably increased its wear resistance. • Hammering alone does not produce well-defined nanocrystalline structure. • The recovery treatment helped turn the dislocation cells generated by hammering into nano-grains, benefiting the wear resistance of AZ31 with improved toughness while retaining desired hardness. [ABSTRACT FROM AUTHOR]

The electrode potential or galvanic series is usually used to reflect the nobility of metals and semi-metals. However, this potential is environment-dependent and the intrinsic nobility of a metal is ultimately governed by its electron stability, which can be represented by the electron work function (EWF). This article reports our studies on the corrosion behavior of isomorphous Cu–Ni alloy in HCl and NaCl solutions, respectively. It was demonstrated that the EWF of the alloy increased as the Ni concentration was increased, so did the corrosion resistance in the acidic solution. In the sodium chloride solution, however, the trend was reversed due to adsorption, hydrolysis and the formation of oxide scale on Cu-rich samples, which more or less prevented them from further corrosion in this solution. In order to confirm this, corrosive wear tests were performed to analyze the performance of the alloy when the effect of oxide scale was eliminated or minimized by the mechanical action. [ABSTRACT FROM AUTHOR]

Electron work function (EWF), adhesion and friction coefficient of three passive alloys were investigated. During dry sliding tests, surfaces having higher work functions showed larger coefficients of friction. While under oil-lubricated sliding condition, the trend was reversed. It appears that when the surface passive film was damaged, the surface broken atomic bonds became active, leading to larger friction. However, under the oil-lubricated sliding condition, the passive film was retained, resulting in a different trend. Surface adhesive forces of freshly polished surfaces and etched ones were measured using an atomic force microscope. Results of the adhesion measurement are consistent with the behaviors of the alloys observed during the friction tests. [ABSTRACT FROM AUTHOR]

One of advantages of multi-element high-entropy alloys (HEAs) is their flexibility for microstructure manipulation, not only for the distribution of various phases but also the phase compositions, which greatly facilitate obtaining optimal combinations of high strength and high ductility with desired balance. In this study, we tailored a highly ductile AlCrFe 2 Ni 4 alloy using Ti addition, which redistributed and induced various phases, including disordered and ordered FCC phases, large-lattice intermetallic L2 1 phase, nanoscale BCC precipitates, and minor η -Ni 3 Ti phase and MgZn 2 -type Fe 2 Ti Laves phase, etc. With increasing the Ti addition, the high-entropy alloy, AlCrFe 2 Ni 4 Ti x (x = 0, 0.25, 0.5, 1.0, 1.5, 2.0 and 2.5, in molar ratio), had its compressive yield strength considerably increased from 451.4 MPa up to 2105.5 MPa at expense of the fracture strain. The microstructure evolution and phase constituents in the AlCrFe 2 Ni 4 Ti x with the Ti variation in a relatively wide range were characterized in detail and correlated with corresponding changes in mechanical properties of this high-entropy alloy system for further development and effective applications. [ABSTRACT FROM AUTHOR]

In this work, individual influences of Al, Fe and Ni on the microstructure, wear resistance and mechanical properties of high-entropy alloys (Al x CrFe y Ni z Ti 0.2) were studied. Microstructures and phase constituents of the alloys with different values of x, y and z were characterized via Scanning Electron Microscope, Energy Disperse Spectroscopy, and X-ray diffraction. Mechanical properties and wear resistances of the alloys were evaluated, including hardness, micro-hardness, and resistance to abrasive wear. It was shown that with increasing Al content, the FCC phase was replaced by disordered BCC (A2) and ordered BCC (B2) phases, leading to an increase in micro-hardness by ∼73% and a decrease in wear volume loss by ∼78%. Fe also increased the fraction of A2 phase, but reduced hardness by ∼41% and led to a considerable decrease in wear resistance. In contrast, Ni helped form a FCC phase, resulting in a decrease in hardness by ∼35%, and an increase in wear volume loss by ∼73%. Abrasive wear appeared to be the dominant wear mechanism, while the formed oxide scale played a role in improving the wear resistance. Efforts were made to correlate the changes in hardness and wear resistance with changes in microstructure. Among all specimens, AlCrFeNiTi 0.2 and Al 0.5 CrNiTi 0.2 reached the highest wear resistance. The results obtained help shed light on the development of advanced wear-resistant high-entropy alloys via the favorable addition of Al. • Influences of Al, Fe and Ni on microstructure, hardness and wear of AlxCrFeyNizTi0.2 high-entropy alloy were investigated. • Increasing Al content led to a significant increase in hardness by 73% and a decrease in wear volume loss by 78%. • Increasing Fe content lowered hardness and consequently increased the wear volume loss. • Varying Ni of low fraction had little effect on wear of the alloy, which markedly increased as Ni fraction rose to 1.25. [ABSTRACT FROM AUTHOR]

Individual effects of Al and Ti on microstructure, mechanical and tribological properties of CrFe 2 Ni 2 alloy were investigated. Al addition changed the alloy from a FCC phase to a mixture of FCC, A2 and B2 phases, increasing the mechanical strength at slight expense of ductility. While Ti made the alloy composed of the FCC phase with L1 2 -Ni 3 Ti nanoparticles, DO 24 η -Ni 3 Ti and C14 Fe 2 Ti phases. Higher Ti contents caused a brittle Chi phase. The hard phases considerably hardened the Ti-containing alloys but markedly decreased the ductility of the alloys. Al appeared to be unfavorable for the wear resistance possibly due to inadequate balance between strength and weakened ductility, while Ti enhanced the wear resistance thanks to the hard phases. The detailed characterization would help guide tuning relevant HEAs for optimal tribological applications. [ABSTRACT FROM AUTHOR]

The wear resistance of high-entropy alloy (HEA), AlCrFe 2 Ni 4 Ti, can be enhanced by increasing the Ti content, which raises the hardness of the alloy due to the formation of harder phases, including an L2 1 phase with disordered-BCC nano-precipitates, a η -Ni 3 Ti hexagonal phase, and a MgZn 2 -type Fe 2 Ti Laves phase. However, these hard but relatively brittle phases have negative influences on the wear resistance of the alloy if their amount exceeds a certain level, especially when large impact forces or large fluctuations in wearing force are involved. In this work, we added carbon to AlCrFe 2 Ni 4 Ti 2 to reduce the Ti-containing brittle phases and form in situ TiC particles in the metallic matrix with improved ductility. Samples of AlCrFe 2 Ni 4 Ti 2 C X (x = 0, 0.5 and 1.0, in molar ratio) were fabricated by arc melting. The fabricated HEA-matrix with in situ TiC particles showed improved ductility, e.g., the compressive ductility was increased by up to 30%, along with increased ultimate compressive strength, although the yield strength was slightly decreased, compared with the alloy without carbon addition. Wear tests demonstrated that the HEA with in situ TiC particles showed consequently enhanced wear resistance (10%–19% higher). This study demonstrates an effective approach to modify the high-entropy alloy for enhanced wear resistance by eliminating or minimizing Ti-containing brittle phases using carbon to react with Ti, forming in situ TiC particles in a HEA matrix with improved ductility. • High-entropy AlCrFe 2 Ni 4 Ti 2 -C X alloys with in situ synthesized TiC particles were prepared via arc melting. • The added carbon reacted with Ti to form in situ TiC particles, leading to improved ductility through reducing brittle η -Ni 3 Ti and Laves Fe 2 Ti phase. • Wear resistance of the alloy was enhanced due to the in situ TiC particles and improved toughness. • Surface and subsurface cracks caused by wear decreased due to improved ductility/toughness, helping lowering stress concentrations and thus wear. [ABSTRACT FROM AUTHOR]

The Co-free AlCrFeNi HEA has good application prospects for its simple duplex BCC phase structure and attractive mechanical properties. In this work, influences of Ti on corrosion and corrosive wear of AlCrFeNi alloy in salty and acidic solutions were investigated and compared with those of AlCrFeCoNi. Results showed that removing Co led to little influence on hardness but only a slight decrease in corrosion resistance. However, the corrosive wear resistance was significantly improved, which was attributed to improved ductility, which benefited the toughness, of the Co-free AlCrFeNi alloy. AlCrFeNiTi 0.5 showed the lowest passivation current and its corrosion current density was only about one-third that of SS316. A strong correlation was found among the corrosive wear resistance, corrosion resistance, hardness and brittleness. Titanium can improve the anti-corrosive wear ability of AlCrFeNi alloy with increased hardness, higher corrosion resistance, and enhanced protectiveness of formed surface oxide film. However, as the Ti content exceeded a certain level, corrosive wear of Ti-containing alloys was accelerated by easy formation of crack and delamination in substrate which led to a negative effect on the corrosive wear resistance, although the alloys showed higher hardness. • Removing Co significantly improves corrosive wear resistance attributing to enhanced ductility of AlCrFeNi alloy. • Ti promotes the formation of continuous protective film on AlCrFeNiTi x. • AlCrFeNiTi 0.5 shows the highest corrosion resistance. • Corrosive wear of AlCrFeNiTi x is reduced with increasing Ti until x = 1 due to increased hardness and the more protective passive film. • Corrosive wear of less tough AlCrFeNiTi 1.5 increases due to local fracture in addition to wear-corrosion synergy. [ABSTRACT FROM AUTHOR]

AlCoCrFeNi is one of the early studied high-entropy alloys (HEAs), attracting considerable attention due to its attractive mechanical properties. Efforts have been continuously made to improve properties of the HEA by modifying its composition. In this study, WC particles were added to AlCoCrFeNi alloy with different percentages (10, 30 and 60 wt%) using an arc furnace. Since medium-entropy alloys with fewer elements may also possess attractive properties with less structural complication, we also added WC to the Co-free medium-entropy alloy, AlCrFeNi, in comparison with its high-entropy HEA companion. Microstructure, mechanical properties and resistances against wear, corrosion and corrosive wear of the WC-added alloys were investigated. It was shown that the added WC decomposed and formed in situ carbides. The WC-added AlCrFeNi is harder with a higher wear resistance than the WC-added AlCoCrFeNi. Both the alloys consist of a BCC matrix and carbides in a eutectic state. With increasing the WC content, hardness and wear resistance of the alloys increased. The medium-entropy alloy AlCrFeNi showed better performance than AlCoCrFeNi. For comparison, Co-WC composite alloy was also prepared using the arc furnace. The wear volume loss of AlCrFeNi-60 wt%WC was only half that of Co-60 wt%WC under the same wearing condition. The Co-containing alloy, e.g., AlCoCrFeNi+60WC, showed its corrosion resistance lower than that of Co-free AlCrFeNi-60 wt%WC, mainly due to its lower %Cr. The addition of WC significantly reduced the volume loss caused by corrosive wear in the 3.5 wt% NaCl solution for both alloys as a result of improved hardness. • AlCrFeNi-WC and AlCoCrFeNi-WC alloys were synthesized by arc melting. • Co-free medium-entropy alloy AlCrFeNi is stronger than the high-entropy alloy AlCoCrFeNi. • WC addition increased the wear resistance and hardness of the alloys at the expense of ductility. • The WC addition increased corrosion of the alloys in salty water due to enhanced galvanic effect. • The MEA-WC and HEA-WC are superior to Co-WC, and are promising for hardfacing overlays. [ABSTRACT FROM AUTHOR]

Mechanical properties of metals are intrinsically determined by their electron behavior, which is largely reflected by the electron work function ( EWF or φ ). Since the work function varies with temperature, the dependence of material properties on temperature could be predicted via variations in work function with temperature. Combining a hardness – φ relationship and the dependence of work function on temperature, a temperature-dependent model for predicting solid-particle erosion is proposed. Erosive wear losses of copper, nickel, and carbon steel as sample materials were measured at different temperatures. Results of the tests are consistent with the theoretical prediction. This study demonstrates a promising parameter, electron work function, for looking into fundamental aspects of wear phenomena, which would also help develop alternative methodologies for material design. [ABSTRACT FROM AUTHOR]

The orientation distribution of grains (so-called texture) and its evolution almost decisively govern the in-service performance of a polycrystalline material, especially for materials with low crystallographic symmetry. As an important nuclear material, zirconium and its alloys have a hexagonal-close-packed (hcp) crystallographic structure and multiple plastic deformation mechanisms. Among them, deformation twinning, reorienting the basal poles 85.22°, could result in an abrupt and drastic change in the texture. As simulation plays a more and more important role in the design, manufacturing, and service of an end-product, a reliable twinning model is essential for zirconium alloys. Two twinning models, namely the Twinning and De-twinning (TDT) and Predominant Twin Reorientation (PTR) models, were implemented in an Elastic Viscoplastic Self-consistent (EVPSC) framework with the thermal effect accounted for. The EVPSC-TDT and EVPSC-PTR models were applied to study the deformation behavior of a Zircaloy-2 slab under different strain paths. A predictive capability of the two twinning models was assessed by both the macro-mechanical behavior of stress-strain response and Lankford coefficient and the micro-mechanical behavior of texture evolution in terms of both pole figure and texture coefficient. It was found that the TDT model exhibits superior performance to the PTR model, especially in predicting texture development. [ABSTRACT FROM AUTHOR]

Highlights: [•] Usefulness of positron beam measurement for characterization of corrosion layer. [•] The calcium carbonate was deposited on the surface of both HPDC and SVDC alloys. [•] Larger volume fraction of eutectic phase in SVDC alloy than HPDC alloy. [•] Higher corrosion resistance of SVDC alloy than HPDC alloy. [Copyright &y& Elsevier]

Abstract: Wear and corrosive wear involve mechanical and chemical mechanisms and the combination of these mechanisms often results in significant mutual effects. In this paper, tribological behavior, X-ray peak broadening, and microstructure changes of carbon steel AISI 1045 and stainless steel AISI 304 samples under simultaneous wear and corrosion were investigated and the results were compared with those obtained from dry wear tests. 3.5wt.% NaCl solution was used as the corrosion agent and a pin-on-disk tribometer was employed to perform wear and corrosive wear tests. X-ray diffraction measurements have shown that by increasing the applied load, the worn surfaces of carbon steel samples reached a constant strain at which fracture and wear occurred. Whereas in 304 stainless steel samples, by increasing the applied load, broadening of X-ray diffraction peaks was decreased. Wear tests of carbon steel and stainless steel samples have shown smaller weight losses and lower friction coefficient in the presence of corrosive environment. Study of worn surfaces suggested that depending on wear environment and applied load, different features of wear mechanisms were involved. [Copyright &y& Elsevier]

Abstract: Wear and corrosion wear involve mechanical and chemical mechanisms and the combination of these mechanisms often results in significant mutual effects. In this research, wear performances, and texture changes of carbon steel AISI 1045 and stainless steel AISI 304 under simultaneous wear and corrosion were investigated and the results were compared with those obtained from dry wear tests. 3.5wt.% NaCl solution was used as the corrosion agent and a pin-on-disk tribometer was employed to perform wear and corrosion wear tests. Wear tests of carbon steel and stainless steel samples have shown smaller weight losses and lower friction coefficients in the presence of corrosive environment. Texture investigations of the worn samples have shown texture changes after wear and corrosive wear tests. In worn carbon steel samples after dry wear test 〈011)〈100〉Goss texture and {111} gamma fiber component were developed in initially random oriented samples, whereas under corrosive wear conditions, {111}〈011〉fiber texture and {001}〈110〉cube texture were obtained. In stainless steel samples, {112}〈110〉texture component were observed under both dry and corrosive wear conditions, in initially random samples. [Copyright &y& Elsevier]

Originally defined high-entropy alloys (HEAs) are generally in a solid-solution state, which are solution-strengthened by multiple-elements with desired toughness. However, the mixture of multiple elements likely result in certain microstructure features, which could also benefit the HEAs. In this study, AlCrFeCoNi and AlCrFeCoNiTi 0.5 high entropy alloys (HEAs) were fabricated, and their microstructures and sliding wear behaviors (in comparison with stainless steel) were investigated using XRD, SEM, EDS and a pin-on-disc tribometer, respectively. It is shown that the two HEAs consist of ordered Al–Ni/Al–Ni–Ti rich BCC and disordered Fe–Cr rich BCC domains. The AlCrFeCoNi alloy has an intertwined structure with plate-like Fe–Cr rich domains embedded in the Al–Ni rich matrix. The AlCrFeCoNiTi 0.5 alloy shows a similar microstructure but has honeycomb-like Fe–Cr rich interdendrites. The Ti addition markedly increases the hardness of the alloy, leading to considerably enhanced resistance to sliding wear. Through wear tests with and without air-flow to minimize frictional heating along with worn surface analysis, we demonstrate that the Ti addition also enhances the oxide scale, making additional contribution to the wear resistance. • High-entropy alloy, AlCrFeCoNi, has an intertwined microstructure with Al–Ni-rich and Fe–Cr-rich BCC domains. • Adding Ti to AlCrFeCoNi induces honeycomb-like Fe–Cr-rich interdendrites. • The Ti addition markedly increases hardness of AlCrFeCoNi, considerably enhancing its wear resistance. • The Ti addition improves the oxide scale, reducing wear when frictional heating is large enough to induce oxidation. • 316 SS showed less wear than AlCrFeCoNi when oxidation was involved, benefiting from its stronger oxide scale. [ABSTRACT FROM AUTHOR]