Search

The peculiarities and modes of material modification with high-intensity, high-power density ion beams on the irradiated surface are studied for the first time. Chromium ions are implanted into a zirconium alloy using a 25 kW/cm2, 450 μs beam at the pulse repetition rates within 8–35 pps. Every high-energy ion pulse impact is followed by ultrafast cooling of the surface due to heat removal into the target material. Three modes are studied at the temperatures of 580, 700, and 900 °C with an additional pulsed heating. An increase in the average target temperature from 580 to 700 °C within 1 h at the same pulse power density allows increasing the depth of chromium ion alloying from 1.5 to more than 7 μm. The use of ultrafast cooling of the Zr1%Nb alloy surface offers a grain size reduction from a few μm to approximately 50–250 nm, without any microstructural changes throughout the sample volume. An inhomogeneous chromium ion distribution over the target surface and depth is observed. [ABSTRACT FROM AUTHOR]

The surface properties of nickel-based alloys with different alloying compositions against aggressively corrosive species were systematically evaluated by using the segregated and non-segregated models designed through first-principles calculations. The presence of typical VIB alloying elements such as chromium (Cr), molybdenum (Mo), and tungsten (W) elements near the nickel surface was identified to significantly enhance the surface adsorption of water molecules (H2O) and their decomposed products (OH, O, and H). The doping patterns and surface electronic structures were found to determine the adsorption diversity of these substances. Consequently, adsorbates containing oxygen were likely to induce the segregation tendencies of these selected alloying elements from the deep area of nickel toward the top-most surface layer (TSL). The electrode potential shifts of the surface Ni atom in the designed alloying systems, compared to the bare Ni (111) surface, were further calculated to identify the beneficial electrochemical performance of alloy surfaces in the absence/presence of various adsorbates. In vacuum, the locations of these alloying elements in the near-surface layers would more increase the electrode potential shifts, thereby delaying the dissolution of Ni atoms from metal substrates. Nevertheless, the presence of adsorbates led to notably negative electrode potential shifts for the Ni (111) surface, among which the decomposed products (hydroxyl and oxygen) were of the most passive effects on corrosion behavior of nickel. The detrimental effects of these adsorbates on surface stability would be effectively alleviated with the aid of atomic VIB alloying elements of nickel-based alloys, especially W segregation to the TSL regardless of the pH in aqueous environments. [ABSTRACT FROM AUTHOR]

ABSTRACT The coefficient of friction of low carbon chromium alloy steel with military grade lubricant was high, resulting in increased heat generation and temperature rise of the lubricant in the aircraft power transmission units such as engine gearbox, accessory gearbox and so on. To address this, the current research proposes the addition of TiO2 nanoparticles to MIL grade lubricant as an additive to enhance the tribological performance. In this experimental study, TiO2 nanolubricant was prepared using various surfactants for better suspension of TiO2 nanoparticles, and properties were evaluated for both base lubricant and nanolubricant. The tribological experiments were conducted using a four ball tester, a shear stability tester and a reichert tester. In a four ball test, TiO2 nanolubricant resulted in a 27.3% reduction in wear scar diameter by the addition of TiO2 nanoparticles to the base lubricant. In a shear stability test, TiO2 nanolubricant showed 80% better shear stability than the base lubricant. In the reichert test, the coefficient of friction was reduced by 13% with the TiO2 nanolubricant. The experimental findings demonstrated that the TiO2 nanoparticles, as an additive to a military grade lubricant, have superior tribological properties for aerospace applications. [ABSTRACT FROM AUTHOR]

The study investigated the effect of retrogression and re-aging (RRA) on the structure and properties of the new Al–3.5Zn–3.5Mg–3.5Cu–1.6Er–0.2Zr–0.2Cr alloy through the use of scanning electron microscopy, thermodynamic calculations, hardness tests, current density, and corrosion potential. During the crystallization process, chromium is distributed between primary intermetallic compounds with an approximate composition of (Al,Zn)79.8Mg4.7Cu3Cr5.5(Er,Ti)7, with a size of approximately 10 μm and an aluminum solid solution. Following two-stage homogenization heat treatment, the Al8Cu4Er and Mg2Si phases exhibit minimal morphological changes, with the θ‑phase (Al2Cu) being completely dissolved and the T‑phase (Al,Zn,Mg,Cu) transformed into the S‑phase (Al2CuMg). Thermodynamic calculations indicate that the alloy should also contain the Al3Zr and Al45Cr7 phases, which precipitate from the supersaturated solid solution during homogenization. Age hardening in the temperature range of 150–210 °C occurs due to the release of metastable modifications of the T‑phase. The combination of hardness (140 HV) and corrosion resistance (minimum corrosion current density 1 μA/cm2) is optimized by retrogression and re-aging. [ABSTRACT FROM AUTHOR]

This study employs thermodynamic-diagram analysis to investigate component ratios within the Fe-Al-Si-Cr system, focusing on the behavior of homogeneous liquid states. Through comprehensive modeling, a phase diagram is constructed, elucidating the interplay of iron, aluminum, silicon, and chromium components. This study identifies stable elementary tetrahedra within the system, providing insights into phase compositions and distribution. Key findings reveal the significance of tetrahedral geometry in understanding and optimizing alloy compositions, particularly in the context of complex chromium alloys. This research underscores the utility of thermodynamic analysis in advancing our understanding of alloy systems and facilitating the optimization of production processes. [ABSTRACT FROM AUTHOR]

Microbiologically Influenced Corrosion (MIC) poses a significant challenge to various industries, leading to substantial economic losses and potential safety hazards. Despite extensive research on the MIC resistance of various materials, there is a lack of studies focusing on High Chromium White Iron (HCWI) alloys, which are widely used in wear-resistant applications. This study addresses this knowledge gap by providing a comprehensive investigation of the MIC resistance of three HCWI alloys with varying chromium contents (22 wt%, 30.7 wt%, and 21 wt%) in the presence of Pseudomonas aeruginosa (P. Aeruginosa), a common bacterial species associated with MIC. The alloys were exposed to an artificial seawater medium inoculated with P.Aeruginosa for 14 days, and their corrosion behaviour was evaluated using electrochemical techniques, surface analysis, and microscopy. Electrochemical Impedance Spectroscopy (EIS) results revealed that the alloy with the highest chromium content (A2, 30.7 wt% Cr) exhibited superior MIC resistance compared to the other alloys (A1, 22 wt% Cr and M1, 21 wt% Cr). The enhanced performance of alloy A2 was attributed to the formation of a more stable and protective passive film, as well as the development of a more compact and less permeable biofilm. The EIS data, interpreted using equivalent circuit models, showed that alloy A2 had the highest charge transfer resistance and the lowest biofilm capacitance, indicating a more effective barrier against corrosive species. Bode plots further confirmed the superior corrosion resistance of alloy A2, with higher impedance values and phase angles at low frequencies compared to alloys A1 and M1. Scanning Electron Microscopy (SEM) and optical microscopy analyses corroborated these findings, showing that alloy A2 had the lowest pit density and size after 14 days of exposure. The insights gained from this study highlight the critical role of chromium content in the MIC resistance of HCWI alloys and have significant implications for the design and selection of materials for applications prone to microbial corrosion. [ABSTRACT FROM AUTHOR]

Aerosols deposited on the surfaces of alloys and coatings used in high-temperature applications react with the protective thermally grown oxide (TGO) and accelerate component degradation. Understanding how the TGO composition effects these reactions is essential to develop corrosion-resistant materials. This work studies the corrosion of Haynes-214 alloy, which forms a bilayer Ni(Cr,Al)2O4 (spinel) + Al2O3 TGO, exposed to complex oxide and sulfate deposits to understand how the Cr and Ni oxides affect the corrosion mechanisms. The deposit compositions were systematically varied to understand the effect of anion makeup (mixed oxides, oxide-sulfate, and sulfates). The results are compared to a FeCrAlY alloy that forms a simple Al2O3 TGO. On the Haynes-214 alloy, deposits containing mixed oxides (with or without sulfates) have limited corrosive effect. In contrast, a pure CaSO4 deposit reacts aggressively with the TGO to form calcium chromate and aluminate reaction products (RP) that substantially increase the TGO + RP thickness compared to that on the FeCrAlY alloy. Surprisingly, a deposit composed of a mixture of sulfates caused less severe corrosion than the CaSO4 alone since magnesium chromate formation appears to limit aggressive reactions involving Ca. The results are discussed in the context of opportunities for corrosion-resistant alloy design. [ABSTRACT FROM AUTHOR]

In this study, SEM, AFM, TEM, XPS, and electrochemical tests are used to study the passivation behavior of chromium alloyed high-strength rebar in simulated concrete pore (SCP) solutions with different pH values. The results show that after passivation in SCP solution with different pH values, the passivating film on the surface of the chromium alloyed rebar primarily consists of a layer of nanoscale oxide particles, which makes the passive film exhibit a p-n type semi-conductor, and the passive film presents a rhombohedral crystal structure. As the pH value of the SCP solution decreases, the nanoscale oxide particles on the surface of the rebar become denser, which leads to a reduction in the carrier density (Nq and Na) of the passive film and an increase in film resistance (R2) and charge transfer resistance (R3), thus increasing the corrosion resistance of the passive film. The passive film on the surface of the chromium alloyed high-strength rebar predominantly exhibits a three-layer structure, the outer passive film layer is composed of Fe oxides, the stable layer of the passive film is composed of Fe oxides and Cr oxides, and the growth layer of inner passive film is composed of Cr oxides. Compared with passivation 10 d in SCP solutions with pH 13.5 and pH 12.5, the passive film on the surface of the rebar has good stability at pH 10.5, which indicates that the addition of Cr is beneficial to promote the corrosion resistance of the rebar. [ABSTRACT FROM AUTHOR]

Refractory high-chromium alloy VZh159 (Haynes 282) obtained by the method of selective laser melting (SLM) is studied. C-curves of the precipitation of particles of a topologically closed-packed (tcp) phase are plotted for the temperature range of heat treatment and operation. It is shown that the content of the tcp-particles of unfavorable morphology increases and the ductility of the synthesized material during synthesis in a protective nitrogen environment decreases with increase in the chromium content in the alloy. The intensification of the precipitation of the particles of the tcp-phase is associated with decrease in the solubility of chromium in the solid solution at high temperatures due to elevation of the nitrogen content in the alloy. To stabilize the alloying system, the chromium content in alloy VZh159 is reduced by 1 wt.% with respect to the upper and lower alloying limits as compared to the deformable counterpart, which makes it possible to prevent marked lowering of the ductility of VZh159 fabricatedby SLM. [ABSTRACT FROM AUTHOR]

To improve their performance, this research characterized the effects of Si on various attributes of high-Cr white cast irons. Hypoeutectic alloys of 15 and 25% Cr white irons were produced with Si levels varying of 0.4, 1 and 1.6%Si and poured into 3-inch (75-mm) Y-block sand molds. Various tests were used to determine the optimum hardening temperature and the kinetics of pearlite transformation. In addition, image analysis was performed to determine eutectic carbide fraction. Furthermore, energy-dispersive spectroscopy analysis was conducted to determine the distributions of the alloying elements among the various solidification constituents. Raising Cr from 15 to 25% caused the optimum hardening temperature to rise from 1680 to 1920 °F (915 to 1050 °C). In the 15% Cr series, an increase of 1.2% Si raised the optimum hardening temperature by 80 °F (50 °C), whereas, for the 25% Cr series, the optimum hardening temperature was unchanged. Peak hardness was significantly higher (by 50 HB) in the leaner Cr alloys and the peak hardness in both the 15% and 25% Cr alloys decreased slightly (by 20 HB) when the Si content was increased from 0.4 to 1.6%. However, the hardenability (the time to the onset of pearlite transformation) increased with increasing Si content. The influence of Si on % eutectic saturation was not clear. When analyzing carbide fraction, Si had a negligible effect in the 15%Cr series, but seemed to cause the 25%Cr series to develop less eutectic carbide, that is, become more hypoeutectic. Cr was richest in the eutectic carbides and leanest in the eutectic austenite matrix. Si was largely rejected from the eutectic carbides and richest in the eutectic austenite. [ABSTRACT FROM AUTHOR]

P92 heat-resistant steel has been successfully submerged arc welded by employing designed CaF2–Cr2O3 fluxes. It has been demonstrated that δ-ferrite is retained in the weld metal, the area fraction of which is found an approximately 3.7-fold enhancement as the Cr2O3 content in the fluxes is raised from 5 to 25 wt pct. Such phenomenon has been elucidated through governing element transfer behaviors incurred by the decomposition of Cr2O3. Our findings possibly offer a viable solution towards developing welding fluxes geared towards durable heat-resistant steel grades. [ABSTRACT FROM AUTHOR]

This study explores the optimization of ultrasonic horn heat treatment conditions for enhanced mechanical quality (Qm). The optimal parameters identified are a tempering temperature of 529°C and a 240-min soaking time, yielding a 1.3% experimental error. Frequency stability during welding is significantly improved, with the optimal horn exhibiting a minimal frequency variation of 64 Hz compared to 90 Hz and 82 Hz for other samples. Hardness varies with tempering temperature, reaching a peak of over 39.3 HRC at 450°C and dropping to 23.8 HRC at 650°C. Microstructural analysis reveals transformations in pearlite, spheroidization, and increased grain sizes in the optimal sample. Carbide precipitation is more pronounced in longitudinal sections and increases with higher tempering temperatures and soaking times. The presence of chromium alloying elements in SCM440 steel contributes to carbide formation. These findings underscore the critical role of heat treatment conditions in optimizing the performance of ultrasonic horns. [ABSTRACT FROM AUTHOR]

The results of studies on the preparation of highly dispersed bimetallic materials based on platinum with chromium, molybdenum, and tungsten under autoclave conditions at 190°C are summarized in this report. The thermodynamic and chemical features of the interactions between [Pt(NH3)4]Cl2 and (NH4)2CrO4, (NH4)2MoO4 and (NH4)2WO4 are considered. Solid products (powders) are represented by two phases—Pt and disordered solid solutions based on platinum. The morphology of powders has been studied—spherical particles with a diameter of 300–700 nm form agglomerates up to 2 µm. A route for the reduction of platinum (II) and oxometalate anions to the corresponding metals with intrasphere ammonia is proposed. The results of this work can form the basis for the synthesis of catalysts that are widely used in a number of industrially important reactions. [ABSTRACT FROM AUTHOR]

Cr3+-activated near-infrared (NIR) phosphors are key for NIR phosphor-converted light emitting diodes (NIR pc-LED). While, the site occupancy of Cr3+ is one of the debates that have plagued researchers. Herein, Y2Mg2Al2- Si2O12 (YMAS) with multiple cationic sites is chosen as host of Cr3+ to synthesize YMAS: xCr3+ phosphors. In YMAS, Cr3+ ions occupy simultaneously Al/SiO4 tetrahedral, Mg/AlO6 octahedral, and Y/MgO8 dodecahedral sites which form three luminescent centers named as Cr1, Cr2, and Cr3, respectively. Cr1 and Cr2 relate to an intermediate crystal field, with transitions of ²E→4A2 and 4T2→4A2 occurring simultaneously. As Cr3+ concentration increases, the 4T2→4A2 transition becomes more pronounced in Cr1 and Cr2, resulting in a red-shift and broadband emission. Cr3 consistently behaves a weak crystal field and exhibits the broad and long-wavelength emission. Wide-range NIR emission centering at 745 nm is realized in YMAS: 0.03Cr3+ phosphor. This phosphor has high internal quantum efficiency (IQE = 86%) and satisfying luminescence thermal stability (I423 K = 70.2%). Using this phosphor, NIR pc-LEDs with 56.6 mW@320 mA optical output power is packaged and applied. Present study not only demonstrates the Cr3+ multi-site occupancy in a certain oxide but also provides a reliable approach via choosing a host with diverse cationic sites and local environments for Cr3+ to achieve broadband NIR phosphors. [ABSTRACT FROM AUTHOR]

The requirement for high-performance and energy-saving materials motivated the researchers to develop novel composite materials. This investigation focuses on utilizing aluminum alloy (A383) as the matrix material to produce hybrid metal matrix composites (HMMCs) incorporating boron carbide (B4C) and multi-walled carbon nanotube (MWCNT) through a cost-effective stir casting technique. The synthesis of HMMCs involved varying the weight fractions of B4C (2%, 4%, and 6%) and MWCNT (0.5%, 1%, and 1.5%). The metallographic study was carried out by field emission scanning electron microscopy (FESEM) mapped with EDS analysis. The results indicated a uniform dispersion and robust interfacial interaction between aluminum and the reinforced particles, significantly enhancing the mechanical properties. Micro-hardness and wear characteristics of the fabricated HMMCs were investigated using Vickers microhardness testing and the pin-on-disc tribometer setup. The disc is made of hardened chromium alloy EN 31 steel of hardness 62 HRC. The applied load was varied as 10N, 20N, 30N with a constant sliding speed of 1.5 m/s for different sliding distances. The micro-hardness value of composites reinforced with 1.5 wt% MWCNT and 6 wt% B4C improved by 61% compared to the base alloy. Additionally, the wear resistance of the composite material improved with increasing reinforcement content. Incorporating 1.5% CNT and 6% B4C as reinforcements results in the composite experiencing about a 40% reduction in wear loss compared to the unreinforced aluminum alloy matrix. Furthermore, the volumetric wear loss of the HMMCs was critically analyzed with respect to different applied loads and sliding distances. This research underscores the positive impact of varying the reinforcement content on the mechanical and wear properties of aluminum alloy-based hybrid metal matrix composites. [ABSTRACT FROM AUTHOR]

To evaluate the marginal accuracy of soft-milled cobalt-chromium (Co-Cr) compared to other construction methods/restorative materials in tooth/implant-supported restorations. Materials and Methods: PICO questions were defined, and a systematic search was conducted in six electronic databases. Titles and abstracts were collected and screened by two independent reviewers. After removing duplicate articles, the full texts of relevant articles were gathered, and the required information and data were extracted. Risk of bias was assessed and meta-analyses of the collected data were conducted using STATA software version 16. Results: A total of 1,914 experimental and clinical articles were reviewed, and 18 studies were selected for qualitative analysis. The 16 studies that were included in the meta-analysis showed no significant marginal gap differences between soft-milled Co-Cr and the following methods/materials: hardmilled Co-Cr (I2 = 92.9%, P = .86), casting wax (I2 = 90.9%, P = .42), laser-sintered Co-Cr (I2 = 93.3%, P = .46), and zirconia (I2 = 0.00%, P = .47). However, a significantly higher marginal accuracy of soft-milled Co-Cr was observed when compared to milled-wax casting (I2 = 93.1%, P < .001). Conclusion: The marginal gap of soft-milled Co-Cr restorations is within the acceptable clinical range and provides an accuracy similar to other available methods/materials for both the prepared implant abutment and tooth. [ABSTRACT FROM AUTHOR]

Chromium- and cobalt-based alloys, as well as chrome–nickel steels, are most used in dental prosthetics. Unfortunately, these alloys, especially nickel-based alloys, can cause allergic reactions. A disadvantage of these alloys is also insufficient corrosion resistance. To improve the properties of these alloys, amorphous Si (C,N) coatings were deposited on the surfaces of metal specimens. This paper characterizes coatings of silicon carbide nitrides, deposited by the magnetron sputtering method on the surface of nickel–chromium alloys used in dental prosthetics. Depending on the deposition parameters, coatings with varying carbon to nitrogen ratios were obtained. The study analyzed their structure and chemical and phase composition. In addition, a study of surface wettability and surface roughness was performed. Based on the results obtained, it was found that amorphous coatings of Si (C,N) type with thicknesses of 2 to 4.5 µm were obtained. All obtained coatings increase the value of surface free energy. The study showed that Si (C,N)-type films can be used in dental prosthetics as protective coatings. [ABSTRACT FROM AUTHOR]

A method for obtaining composite surface-alloyed castings from gray cast iron SCh25 by cavityless casting with the use of master alloys containing chromium and ferroboron deposited as a paste layer on the surfaces of the casting molds is considered. The microstructure and the phase composition of the surface layer and the microhardness of the structural components are determined. Mechanical tests of the cast samples for compression and wear are carried out. Self-propagating high-temperature synthesis is shown to occur between the components of the master alloys deposited on the surfaces the molds during the production of the castings. The types and compositions of the borides and carboborides formed in the alloyed layer are determined. The effect of the parameters of the alloyed layer on the properties of the composite castings is analyzed. [ABSTRACT FROM AUTHOR]

This study describes the strengthening mechanisms of an ultrafine-grained (UFG) Fe35Mn27Ni28Co5Cr5 high-entropy alloy (HEA) processed by severe cold rolling (SCR) process at room temperature. Microstructural evaluations were performed by field emission scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The findings demonstrated that the development of deformation microstructures consisted of a single face-centered cubic (FCC) phase with stretched grains along the rolling direction and lamellar deformation bands after a 90 % reduction in thickness. Using the Nix-Gao model, the dislocation density was determined by measuring the microhardness indentation size effect. The results indicated that an increase in rolling deformation leads to an increase in dislocation density. The dislocation density increased from 2.28 x 109 cm-2 for as-homogenized specimen to 8.65 x109 cm-2 after 90 % reduction in thickness. The yield strength of the UFG Fe35Mn27Ni28Co5Cr5 HEA was 5.2 times (1155 MPa) higher than that of the as-homogenized state (225 MPa). Finally, an assessment was conducted on the relative contributions of individual mechanisms, such as dislocation and grain refinement, to the strengthening of the Fe35Mn27Ni28Co5Cr5 HEA. [ABSTRACT FROM AUTHOR]

Aseptic implant loosening after a total joint replacement is partially influenced by material-specific factors when cobalt–chromium alloys are used, including osteolysis induced by wear and corrosion products and stress shielding. Here, we aim to characterize a hybrid material consisting of alumina-toughened zirconia (ATZ) ceramics and additively manufactured Ti-35Nb-6Ta (TiNbTa) alloys, which are joined by a glass solder. The structure of the joint, the static and fatigue shear strength, the influence of accelerated aging, and the cytotoxicity with human osteoblasts are characterized. Furthermore, the biomechanical properties of the functional demonstrators of a femoral component for total knee replacements are evaluated. The TiNbTa-ATZ specimens showed a homogenous joint with statistically distributed micro-pores and a slight accumulation of Al-rich compounds at the glass solder–TiNbTa interface. Shear strengths of 26.4 ± 4.2 MPa and 38.2 ± 14.4 MPa were achieved for the TiNbTa-ATZ and Ti-ATZ specimens, respectively, and they were not significantly affected by the titanium material used, nor by accelerated aging (p = 0.07). All of the specimens survived 107 cycles of shear loading to 10 MPa. Furthermore, the TiNbTa-ATZ did not impair the proliferation and metabolic activity of the human osteoblasts. Functional demonstrators made of TiNbTa-ATZ provided a maximum bearable extension–flexion moment of 40.7 ± 2.2 Nm. The biomechanical and biological properties of TiNbTa-ATZ demonstrate potential applications for endoprosthetic implants. [ABSTRACT FROM AUTHOR]

The effect of a minor amount of rare-earth element Nd addition (0.1 at%) on the microstructural properties, microhardness, and cyclic oxidation resistance of NiAl–Cr(Mo) alloy is investigated in detail. The microstructure of investigated alloys is composed of NiAl-based dendrites and a eutectic mixture whose components are NiAl and Cr(Mo) phases. The minor amount of Nd addition refines the microstructure and increases the microhardness considerably. The results of the cyclic oxidation tests reveal that the surface scales of both alloys are mainly consisted of α-Al2O3 and little amount of Cr2O3. A Cr(Mo)-rich layer is observed in the metal/oxide interface. With Nd addition, the oxidation resistance of Ni–33Al–31Cr–3Mo alloy is strongly improved. The Nd-added alloy exhibits lower oxidation mass gain and increased scale adherence. [ABSTRACT FROM AUTHOR]

The effect on the structural phase state and mechanical properties of the composition of the parameters of obtaining nanocomposite and nanolayer wear-resistant coatings based on Cr, W, and N, obtained by the method of magnetron sputtering was investigated in this work. CrWN nanocomposite coatings were precipitated by the magnetron method with DCMS permanent magnets from a complex target consisting of Cr and W with different ratios of components by area. Electron microscopic studies of the obtained CrWN coatings showed a nanocrystalline finely dispersed structure with a grain size of up to 30 nm. From the analysis of the elemental composition of the coatings, a clear correlation can be observed between the composition of the target and the composition of the resulting coating. For CrN/WN nanolayer coatings, two metal targets of pure Cr and W were used, and coatings of chromium nitride and tungsten nitride were applied sequentially by magnetron sputtering. A dense and smooth microstructure of multilayer coatings was obtained. The presence of a nanolayer structure was confirmed and the sequential change of CrN and WN layers was shown. Smooth and clear interfaces between the CrN and WN layers were observed, indicating a dense and well-packed configuration of the multilayer coating. The CrN/WN nanolayer coatings showed a high hardness of about 30 GPa, which was higher than that of the CrWN nanocomposite coating, where the hardness was about 23 GPa. [ABSTRACT FROM AUTHOR]

Valence electron concentration (VEC) analysis of high-entropy alloys (HEAs) has been extended to a scheme using a two-parameter plot by introducing the period of the periodic table as the second variable. The extension aimed to include HEAs with a hexagonal close-packed (hcp) structure comprehensively in the framework of VEC analysis, along with other HEAs with body- and face-centered cubic (bcc and fcc) structures. A statistical analysis using a VEC–period chart was performed for 261 single-phase exact- and near-equiatomic HEAs with bcc, hcp, or fcc structure acquired from the literature. Supplemental experiments were conducted in the present study for an hcp-Co35Cr20Fe15Ru20V10 alloy (Ru20 alloy) predicted by Thermo-Calc software and the TCHEA6 database. The experiments revealed that the water-quenched Ru20 alloy annealed at 1600 K for 1 h exhibited a single hcp structure. The formation of the hcp-Ru20 HEA was attributed to the inclusion of a minimum amount of 20 at%Ru, as an hcp forming element, from a 4d-transition metal (TM). The Ru20 alloy with (VEC, Period) = (7.65, 3.2) was located immediately below the conventional fcc-HEAs plotted along the segment of (VEC, Period) = (8–9.5, 3). The VEC-period chart revealed a strict boundary of the hcp/fcc regions in the VEC–period chart between the Ru20 alloy and fcc-HEAs. It is practically difficult to prepare hcp-HEAs comprising 3d-TM only through conventional solidification from a melt and subsequent annealing, as required. [ABSTRACT FROM AUTHOR]

A coating prepared via laser cladding has the advantages of a high-density reinforced layer, a low matrix dilution rate, and combination with matrix metallurgy. In this study, Ni3Al-based alloy cladding layers with Cr7C3 were prepared via laser cladding, and the corresponding microstructures and wear resistance were studied in detail. The results show that the Ni3Al-based cladding layer prepared using laser cladding technology had good metallurgical bonding with the matrix, and there were no pores, cracks, or other defects on the surface. The microstructures of the laser cladding layer were mainly γ′-Ni3Al, β′-NiAl, and in situ C7C3. As the laser power increased, the heat input increased, resulting in an increase in the dilution rate. Simultaneously, the carbide size in the laser cladding layer increased. With the increase in laser power, the hardness of the laser cladding layer of the Ni3Al-based alloy decreased, and the wear resistance of the laser cladding layer first strengthened and then weakened. When the laser power increased to 2.0 kW, the wear rate of the laser cladding layer decreased to 0.480 × 10−5 mm3/N·m. When the laser power increased to 2.4 kW, the wear rate of the laser cladding layer increased to 0.961 × 10−5 mm3/N·m, which was twice the rate at 2.0 kW. This could be attributed to small Cr7C3 particles, which could not effectively separate the wear pairs, resulting in more serious adhesive wear. Large Cr7C3 particles caused the surface of cast iron material with lower hardness to be damaged, which suffered more serious particle wear. The generation of short rod-shaped carbides should be avoided because, in the process of friction and wear, carbides with these shapes are easy to break, thus leading to crack initiation. [ABSTRACT FROM AUTHOR]

Yttrium-stabilized zirconium (YSZ) thermal barrier coatings (TBCs) are applied in gas turbines due to their ability to shield metallic parts from exposure to high temperatures. The progress in this area is sought out, among others, by bond coat (BC) engineering providing a better stress relief at ceramic/metal boundary and excellent both oxidation and corrosion protection of the metallic substrate. The present BC based on NiAl intermetallic, being exposed to oxidizing atmosphere at high temperature, secure formation of Al2O3 layer fulfilling both these requirements. The NiCr alloys are not only capable to produce a dense Cr2O3 layer at the ceramic/BC boundary, but it may additionally offer closer coefficient of thermal expansion (CTE) to that of the metallic substrate. The aim of this work was a detail characterization of the microstructure, phase and local chemical composition of the TBC consisting of YSZ (ZrO2 with 8 wt.% of Y2O3) top coat (TC) and Ni 50 wt.% Cr bond coat. They were deposited over 321 s stainless steel substrates using a detonation gun (DG) technique. The investigations were performed with scanning and transmission electron microscopy backed with energy-dispersive x-ray spectroscopy (SEM/TEM/EDS). The high-temperature (HT) cycling of YSZ/Ni50Cr set was performed in air and comprised of 5 cycles, which consisted of heating the samples up to 900 °C at 10 °C/min., holding them at that temperature for 10 h, followed by their cooling down for ~ 30 min. The microstructure observations showed that DG allowed to produced dense YSZ coating of low porosity, while Ni50Cr bond coat differed in local chemical composition and contained numerous amorphous chromium oxide pockets. During the HT cycling, the oxygen from the air was still able to penetrate through the YSZ layer supporting formation of Cr2O3, while the amorphous chromium oxide transformed to R-CrO2 (rutile type). Only small amount of NiO was noted, being dispersed within Cr2O3. Simultaneously, a significant inter-diffusion of Ni into steel substrate and Fe and Cr into the bond coat were documented. The lack of oxide formation in the substrate proves that the DG YSZ/Ni50Cr set could serve as a good protection over parts subjected to HT cycling. [ABSTRACT FROM AUTHOR]

A series of chromium-doped calcium ferrite samples of composition Ca0.5Mg0.5Fe12−xCrxO19 (x = 0.0, 0.5, 1.0, 1.5, 2.0) was meticulously prepared using the standard sol-gel combustion route. Structural and morphological properties were comprehensively studied via X-ray diffraction and Scanning Electron Microscopy (SEM). The lattice parameters 'a' and 'c' unequivocally validated the space group of the samples as P63/mmc (194). Moreover, the lattice parameters derived from the XRD data demonstrated commendable agreement with the values extrapolated from theoretical cation distribution and Rietveld refinement calculations. It was further confirmed that the crystallite size, as determined by XRD, concurred excellently with the particle size measurements from the scanning electron micrographs. The samples' magnetic characterization was carried out using a vibrating sample magnetometer (VSM). Notably, the saturation magnetization (Ms) and remanence (Mr) were found to exhibit an increase, while coercivity (Hc) displayed a concurrent decrease with higher substitution ratios. The reason behind the enhancement of saturation magnetization and remanence, along with the reduction in coercivity, was elucidated based on involved factors such as crystallite size, anisotropy constant, and cation distribution. Results showed that including chromium significantly softened the ferrite materials, making them ideal for advanced high-end recording applications. The samples also exhibited low coercivity and impressive saturation magnetization, enhancing their value as storage devices tailored for information storage and recording purposes. [ABSTRACT FROM AUTHOR]

This study presents the effect of stoichiometry and annealing condition on Ti–Cr AB 2 -type hydrogen storage alloys. Prior to annealing the majority phase of the as-cast alloys was the C14 Laves phase, with separate Ti and Cr phases. Annealing treatment (1273 K/14 d) led to a transition from C14 to C15 Laves phase structure. Both C14 (as-cast) and C15 (annealed) cell size increased with Ti content, up to a ratio (Cr/Ti) of 1.6, due to B-site Ti substitution in the lattice up to a limit. Pressure composition isotherm (PCI) measurements demonstrated alloys containing a greater Ti content had a better maximum hydrogen storage capacity (1.5 vs. 1.03 wt%) and lower plateau pressure (9.4 vs. 15.8 bar) at 253 K. Annealing resulted in a lower storage capacity (1.05 vs. 1.49 wt%), greater plateau pressure (ca. 30 bar) and flatter plateau slope (25 % reduction in plateau slope). Reduction in hydrogen storage capacity of annealed alloys could be due to diffusion of residual Cr in the alloy into the C15 Laves phase during the annealing process, thereby changing the local composition as confirmed through X-ray diffraction (XRD). • The C14 and C15 cell size for as cast and annealed alloys increased with Ti content. • The increase in cell size indicates (limited) Ti substitution in the lattice. • Cr vacancies are present in smaller deviations away from AB2 stoichiometry. • Greater Ti content leads to high hydrogen storage capacity and low plateau pressure. • Capacity reduces post-annealing due to C15 B-site Cr diffusion and increased oxygen. [ABSTRACT FROM AUTHOR]

Hysteresis of hydrogen storage alloys essentially hinders the compressibility and operation efficiency of metal hydride hydrogen compressors. In this work, minor Al additive was added into Ti–Cr based hydrogen compression alloys through induction levitation melting, and the apparent hysteresis was successfully ameliorated. The XRD and SEM results indicate homogeneous element distribution of a main C14 Laves phase of Ti 0.96 Zr 0.06 Cr 1.0 Mn 0.6 Fe 0.4 Al x (x = 0, 0.01, 0.02, 0.04, 0.08) alloys, and vanishing of a minor oxide phase in case the Al additive is introduced. As Al stoichiometry increases in the alloys, the hydrogenation plateau decreases obviously but the dehydrogenation plateau hardly changes. Meanwhile, the hydrogen capacity ascends initially but descends slightly. Additionally, no severe performance degradation is induced. The mechanism for overall performance improvement can be concluded as dual functions of Al additive: one can be oxide reduction of other elements during melting determined by XPS and ICP, and the other can be partial Al substitution for the B-side elements, leading to relieved deformation energy surrounding the vacant Al-containing interstitials. As to hydrogenation kinetics, the alloys exhibit accelerated hydrogenation rate with increased Al stoichiometry due to decreased activation energy and hydrogenation plateau. Furthermore, the first-principles calculation results indicate random Al substitution for the B-side atoms, and anisotropic expansion of the unit cell can be attributed to Al substitution at 6h sites. This work reveals a simple and effective way to enhance hydrogen storage performance of Ti–Cr based alloys. [Display omitted] • Influence of minor Al additive in Ti–Zr–Cr–Mn–Fe based alloys is investigated. • Hysteresis is remarkably modified by Al additive with overall enhanced performance. • Reduction and substitution dual-effect of Al is key mechanism for modification. • Results of first-principles calculation indicate random Al substitution at B-sites. • Optimum stoichiometry of Al additive should be 0.01–0.04 in the studied alloys. [ABSTRACT FROM AUTHOR]

The oxidation kinetic behavior of Crofer22H alloy at 700–800 °C was investigated. Due to the high oxidation rate exhibited at 800 °C, the xCr-MnCo dual-structured spinel coating was prepared by magnetron sputtering. The element diffusion behavior of the coating/alloy system was changed by control the formation of Cr layer with different thicknesses on the surface. Appropriately increase the thickness of Cr barrier layer can effectively hinders the Fe outward diffusion and improve the antioxidant performance. Fe doped into Mn–Co spinel increased the electron hopping in the crystal structure. Higher electron hopping and thin Cr 2 O 3 layer reduced the electron resistance. • A new xCr-MnCo dual-structured coating was proposed on Crofer22H interconnect. • The Cr barrier layer effectively inhibits the Fe outward diffusion from the alloy. • The spinel coating significantly reduces the oxide layer area specific resistance. • Revealed the oxidation and electrical conductivity mechanism of the coating. [ABSTRACT FROM AUTHOR]

The paper studies the coating consisting of the Al–Cr sublayer and external Y–Al–O ceramic layer obtained by vacuum-arc deposition for the protection of the VTI-4 (Ti49–11Al–40Nb) intermetallic alloy from oxidation at 750°C. The coating degradation mechanism and phase transformations are studied during their heating in a furnace and thermal cyclic tests. Test results show the stability of the double-layer coating in both cases. [ABSTRACT FROM AUTHOR]

Introduction of 0.3% Cr into Al–Cu–Er–Zr alloy leads to significant modification of the grain structure and almost complete elimination of a dendritic structure. The average grain size of 40 μm corresponds to the size of a dendritic cell. The good modifying capacity is explained by formation of intermetallic compounds of the phase first identified of approximate composition Al75–80Cu10–12Er3–4Cr7, which is a substrate for nucleation of primary aluminum. After quenching and aging, slight hardening in the alloy is achieved due to L12 –Al3(Zr,Er) dispersoids with an average diameter of 40 nm and q'(Al2Cu) precipitates with a diameter up to 100 nm and a thickness up to 5 nm. No particles containing chromium are found within the matrix. According to thermodynamic calculations, hot rolling of AlCuErZrCr alloy at a temperature of 440°C should proceed in the ((Al)+Al3Zr+Al7Cr) phase region. However, analysis of the fine structure in an annealed condition after rolling showed presence of only L12 –Al3(Zr,Er) dispersoids. Differences in alloy hardness on annealing up to 300°C may be explained either by the influence of dissolved chromium atoms or by formation of chromium-containing particle clusters, which could not be detected. [ABSTRACT FROM AUTHOR]

Various stability criteria developed for high-entropy alloys are applied to compositions produced by mechanical alloying. While they agree with the annealed samples, these criteria fail to describe the as-milled metastable systems, highlighting the ability of mechanical alloying to overcome the limitations imposed by these criteria. The criteria are based on atomic size (Ω ≥ 1.1 and δ r   ≤   6 .6%) and/or electronegativity misfit, as well as on mixing enthalpy ( Λ > 0.95   J   m o l − 1 K − 1 and − 5   k J   m o l − 1 < ∆ H m i x < 0 ), or purely thermodynamic ( ϕ Y e > 20 ; ϕ K i n g > 1 ; T e f f < 500   K ). These criteria are applied to several compositions found in the literature and to two metastable fcc solid solutions produced by mechanical alloying with compositions Al0.75CoXFeNi with X = Cr and Mn. Single-phase microstructures are stable up to above 600 K, leading to more stable multiphase systems after annealing above this temperature. Mössbauer spectrometry shows that, whereas the alloy with Cr is paramagnetic in the as-milled and annealed state, the alloy with Mn changes from paramagnetic to ferromagnetic behavior (Curie temperature ~700 K) after annealing. Thermomagnetic experiments on annealed samples show for both compositions some hysteretic events at high temperatures (850 to 1000 K), probably ascribed to reversible ordering phenomena. [ABSTRACT FROM AUTHOR]

The influence of the Zn–Cr electrodeposition bath composition, cathode current density under direct current conditions, and the average pulse current density and the current density under pulse plating current conditions on the content of chromium in the obtained Zn–Cr coatings, the current efficiency and their corrosion properties were investigated. The obtained Zn–Cr coatings contained from about 0.01 wt-% to about 10 wt-%. The corrosion resistance largely depended on the chromium content of the coating, but also on the morphology and surface development. The best corrosion resistance was achieved for Zn–Cr alloy coatings obtained under impulse current conditions for average current densities 3 and 4 A dm−2, while cathodic peak current densities were 30 and 40 A dm−2. [ABSTRACT FROM AUTHOR]

This article presents the results of research into the characteristics of cast steel alloyed with chromium and vanadium, subjected to heat treatment for increased strength parameters. In the first part, it discusses the state-of-the-art knowledge regarding technological developments in the field of cast-steel alloys and the influence of individual alloying additives on the microstructure and the properties of the steel alloy. Further sections present the results of microstructure observations performed with light microscopy, scanning electron microscopy, and transmission electron microscopy. This research focuses on the material in the state directly after casting and after heat treatment, which involved quenching and tempering at 200 °C. The microstructural analysis performed as part of this research has informed the discussion of the results obtained from tensile and impact strength tests. The article also includes the results of a fractography analysis performed as the final part of the tests and offers a general summary and conclusions. [ABSTRACT FROM AUTHOR]

High‐entropy alloys (HEAs) made up of multiple metallic elements have gained attention for their excellent electrocatalytic performance. However, their application in the field of nitrogen (N2) oxidation reaction (NOR) remains underexplored. In this study, a "pomegranate‐like" carbon embedded with ultrafine AuPdPtRhIr HEA (HEA@C) is synthesized using a polymer‐confined pyrolysis strategy. Molecular dynamics (MD) simulations show that small‐sized metal nanoparticles formed by the confinement of polyvinyl alcohol (PVA) during the hydrothermal process can easily form a single‐phase HEA through a thermodynamically‐driven solid‐phase diffusion process during subsequent pyrolysis. Additionally, a porous carbon layer which in situ converted from the PVA shell can effectively inhibit the agglomeration of HEA nanoparticles and confine the surrounding N2. Experimentally, the HEA@C nanohybrid demonstrates a satisfactory NO3− yield rate of 23.8 µg h−1 mgcat.−1 and a high Faraday efficiency of 13.8% for the NOR process. By using operando Fourier Transform Infrared spectroscopy, online differential electrochemical mass spectrometry (DEMS), and density functional theory calculations, potential efficient active sites (Rh–Ir–o) and pathways for the electrochemical conversion of inert N2 to NO3− are revealed. This research provides an effective strategy for producing highly dispersed ultrafine HEA nanoparticles, showing a wide range of applications in advanced electrocatalysis. [ABSTRACT FROM AUTHOR]

The effects of Fe substitution by Zr on the microstructure, hydrogen storage properties and oxidation resistance of the TiFe 0.85-x Cr 0.15 Zr x (x = 0, 0.05, 0.10, 0.15) alloys are studied in this work. It is shown that all the alloys are consisted of TiFe phase, MgZn 2 -type phase and minor Ti phase. The introduction of Zr causes no change for the TiFe main phase. All the alloys absorb hydrogen directly under mild conditions without any activation process. As Zr content increases, the maximum hydrogen storage capacity of the first hydrogenation increases while the reversible hydrogen storage capacity decreases. The marked change of the first hydrogenation properties may be due to the formation of the bright phase (MgZn 2 -type phase). The decrease of the reversible hydrogen storage capacity is due to the formation of the stable hydrides Cr 2 ZrH 3 and TiH 2 , which start to decompose at around 700 °C. During the air exposure test, the alloys with higher Zr content show good oxidation resistance. For the PCT measurement, the alloys with higher Zr show lower hydrogen absorption and desorption platform pressure, which means more stable hydrides are formed during the first hydrogenation. Moreover, the rate limiting step model of the first and fifth hydrogenation processes of all the alloys has also been investigated in detail. • TiFe 0.85- x Cr 0.15 Zr x (x = 0, 0.05, 0.10 and 0.15) alloys were prepared. • Regulating Zr content changed effectively the first hydrogenation properties. • MgZn 2 -type phase could act as a pathway to assist hydrogen diffusion. • Oxidation resistance increased with the introduction of Zr content. • Two kinds of irreversible hydrides were formed in the hydrogenation process of the alloys with Zr. [ABSTRACT FROM AUTHOR]

AlMgSi alloys with two Cr compositions (0.17 wt% and 0.08 wt%) were subjected to different homogenization heat treatment soak conditions at: 560 °C, 580 °C, 600 °C with soak time duration of 6 h, 8 h, and 10 h; subsequently, alloys were cooled by air. Metallographic examination methods were used to determine microstructure after homogenization heat treatment. Hardness measurements were used to assess the mechanical properties. The results indicated that high Cr concentration in Al alloy contributed entirely transformation of β-AlFeSi into cubic α-AlFeSi phase with 580 °C–600 °C soak temperature condition. At the same time, high levels of Cr addition led to the formation of higher volume fractions in the alloy. The Mg2Si particles entirely dissolved in the Al matrix and homogeneously dispersed under this annealing condition. The specimens reached maximum hardness after homogenization heat treatment at 580 °C for 8 h. The hardness values of the sample with 0.17 wt% Cr are higher than the sample with 0.08 wt% Cr for relatively long-term soak time at 8 h–10 h and high soak temperature at 580 °C–600 °C. [ABSTRACT FROM AUTHOR]

High-temperature oxidation behavior of conventionally cast and additively manufactured (AM) Co-base alloy MAR-M-509 was compared in the present study. The specimens were exposed in air at 1000 °C and characterized by means of scanning electron microscopy equipped with energy/wavelength dispersive x-ray spectroscopy (EDX/WDX) and electron backscatter diffraction as well as transmission electron microscopy. Substantial differences in the oxidation processes of two alloy versions were observed. Faster oxidation of the cast alloy was mainly induced by (1) oxidation of coarse primary carbides, (2) internal oxidation and nitridation processes and (3) incorporation of other alloy constituents (e.g., Co, Ni, W) into the Cr-oxide scale. AM specimens, in contrast, formed a more homogeneous, thinner and better adherent external oxide scale. The results are discussed in terms of differences in the chemical composition and alloy microstructure, including the grain size distribution in the material and the morphology of the strengthening precipitate phases. [ABSTRACT FROM AUTHOR]

The paper studies the corrosion resistance of 40Cr130 in different structural states. The material is thus characterized in the annealed, normalized, quenched, tempered state and, respectively, following a thermochemical treatment. Good corrosion resistance was found in all states, and substantial improvements were noted following the thermochemical nitriding treatment. [ABSTRACT FROM AUTHOR]

Newly developed materials and manufacturing processes offer different treatment modalities, such new treatment options need investigation and comparison to achieve long lasting, hygienic and health preserving prosthesis. This study was aimed to compare the fitness of three different materials Casted Cobalt Chromium, Selective Laser Melting Cobalt Chromium and Milled Polyoxymethylene (POM) Acetal. SLS Co-Cr shows superior fitness qualities that Acetal and Casted Co-Cr respectively. [ABSTRACT FROM AUTHOR]

The paper presents the results of investigation of the influence of electroslag remelting on the properties of metal of ingots of high-manganese steel, alloyed by aluminium and chromium. Features of structure formation in high-alloy manganese steels are considered. These steels demonstrate ductility and lower density, alongside strength, and are difficult for pouring alloys, prone to hot cracking, formation of a coarse structure and development of macro- and microliquation. Studies have been performed, which confirm the conclusions that steels of this type require a thorough control of solidification conditions. Obtained results illustrate a significant influence of the cooling rate on cracking, manganese and aluminium segregation and parameters of the alloy dendritic structure. Electroslag remelting resulted in improvement of the structure and led to reduction of the size of nonmetallic inclusions in the studied metal without any significant changes in Mn, Al and Cr content, which is one of the conditions for producing large-sized homogeneous ingots. Metallographic examinations showed that the microstructure of all the studied steel specimens is characteristic for austenitic steel with dendritic crystal growth. Dendritic structure in the metal of ESR ingot is homogeneous, distances between the first and second order axes in the ingot middle and upper parts are equal to 136.6-146.5 and 60.54-8.92 μm, respectively. Completing formation of the required final microstructure of the studied steel takes place after further heat and thermodeformational treatment. ESR of cast billets allows reaching the required level of metal homogeneity and specified level of properties with a smaller number of stages and duration of thermomechanical treatment, and reducing resource consumption. [ABSTRACT FROM AUTHOR]

Interdiffusion coefficients in low-Al Fe–Cr–Al alloys at 1000 °C were experimentally determined by using a diffusion-couple method, and the effects of Cr on the interdiffusion flux of Al were evaluated. The main-term interdiffusion coefficients, D ~ AlAl Fe and D ~ CrCr Fe , decreased with increasing Cr content, and the D ~ AlAl Fe values were two to three times greater than the D ~ CrCr Fe values. The cross-term interdiffusion coefficient, D ~ AlCr Fe , was positive, indicating a positive chemical interaction between Cr and Al in the Fe–Cr–Al alloys. D ~ AlCr Fe was one order of magnitude smaller than D ~ AlAl Fe and decreased with increasing Cr content. Because of the positive D ~ AlCr Fe value, when the concentration gradients of Al and Cr had the same sign, the Al interdiffusion flux was increased by Cr and increased with increasing Cr content due to the steeper Cr concentration gradient. [ABSTRACT FROM AUTHOR]

The microstructure and early-stage oxidation behavior of the equiatomic CoCrCuFeMnNi high-entropy alloy (HEA) and its six sub-alloys, obtained by omitting one element each, were investigated. Alloys were prepared using induction levitation melting, cold rolled, and oxidized for 1 h at 800°C in air. The Ni-free and Co-free HEAs showed an inhomogeneous microstructure associated with liquid phase separation. The other alloys were either single-phase (Cu-free HEA) or contained two face-centered cubic phases, one Cu-rich and one Cu-poor. The Cu and Mn-containing two-phase alloys showed preferential oxidation of the Cu/Mn-rich phase, leading to Mn-rich oxides that are prone to spallation. The Mn-free alloy exhibited a thicker oxide (~ 5 µm) on the Cu-rich phase, whereas the Cu-poor phase was covered by a thin base oxide (< 1 µm). The single-phase Cu-free ('Cantor') alloy formed an approximately 1-µm-thick oxide of the crystal structure types of Mn3O4, Mn2O3, MnCr2O4, and Cr2O3. For prospective high-temperature applications, reducing the Cu and Mn content and thus avoiding formation of a second Cu-rich phase is a promising route to facilitate formation of a protective oxide. [ABSTRACT FROM AUTHOR]

In this work, stainless steel pickling sludge (SSPS) and Ni-bearing electroplating sludge (ES) were co-treated to prepare Ni matte and Fe–Cr–Si alloy. A two-stage sulfurization-smelting method was used for preparing the Ni matte. At the sulfurization stage, carbon, SSPS, and ES were mixed and reacted at 1000 °C. It was found that NiO in the SSPS and ES can be sulfurized to (Fe,Ni)0.955S by CaSO4. After that, the sulfurized sludge was smelted at 1450 °C, and the liquid Fe–Ni–S matte was separated from slag by gravity at this stage. The Ni grade (37.5 wt pct) of the matte prepared at a C/CaSO4 molar ratio of 4 was higher than most of the industrial mattes (13 to 35 wt pct). Meanwhile, the recovery efficiency of Ni was 98.1 pct. For recovering Cr, Fe–Cr–Si alloy was prepared by the silicothermic reduction of the smelting slag. The sulfur (0.008 wt pct) and carbon (0.01 wt pct) contents of the Fe–Cr–Si alloy produced were lower than the threshold values for commercial Fe–Cr–Si alloy (0.01 wt pct S, 0.02 wt pct C). Therefore, this alloy can be used for stainless steel making. [ABSTRACT FROM AUTHOR]