Increase In Vickers Hardness Research Articles

Microstructure and ion‐exchange properties of transparent glass–ceramics containing Mg2SiO4 crystals

AbstractTransparent glass–ceramics (GCs) with excellent mechanical properties is a growing demand in the field of optoelectronic devices. In this work, Mg2SiO4 nanocrystals embedded transparent GCs were prepared using the melt‐quenching method. The effects of the TiO2 content on the structural and crystallization properties of glass were examined, and the influence of Mg2SiO4 crystallization on the depth of layer (DOL) for K–Na ion‐exchange was also investigated. The introduction of TiO2 was advantageous for the enhanced bulk crystallization of Mg2SiO4 nanocrystals within the glass matrix. With an increase in the TiO2 content, the size of Mg2SiO4 nanocrystals decreased, leading to an improvement in the transmittance of the GCs. Crystallization of Mg2SiO4 nanocrystals promoted the increase in Vickers hardness and ion‐exchange DOL obviously, and the Vickers hardness can further be improved by ion‐exchange. Ion‐exchange resulted in the transformation of NaAlSiO4 into KAlSiO4. Results reported here are valuable for the design and preparation of GCs with excellent mechanical and ion‐exchange properties.

Novel Ceramic Clay Automatic Feeding System and Simulation Analysis

This study aims to verify the feasibility and effectiveness of an automatic feeding system in the ceramic clay-forming process. Through a series of clay-forming experiments, the system’s performance under various process parameters was examined. Precision sensors and data recording devices were used to monitor and record key data during the experimental process in real-time. The results demonstrate that the automatic feeding system can supply clay steadily and continuously under set parameters, ensuring a smooth forming process and significantly improving efficiency. Quantitatively, the system achieved a 30% increase in Vickers hardness, reflecting enhanced mechanical properties of the formed clay bodies. Additionally, there was a notable improvement in axial stress–strain characteristics, indicating better structural integrity and consistency. These improvements reduced human errors and material waste, enhancing production efficiency and product quality. Future research will focus on further optimizing system design and exploring its applications in a broader range of ceramic manufacturing processes.

Densification and network structural changes in binary aluminosilicate glass via cold sintering process

Binary aluminosilicate glasses containing 20–50 wt% Al2O3 were successfully densified through a cold sintering process (CSP) using 1–10 M NaOH solutions. The investigation focused on densification and structural unit changes in the cold-sintered binary aluminosilicate glasses. Specifically, the binary aluminosilicate glass with 40 wt% Al2O3, cold-sintered at 180 °C using 1–10 M NaOH solutions, achieved a relative density of up to 90 % at 10 M NaOH. This was attributed to an enhanced dissolution-precipitation process facilitated by an increased concentration of the NaOH solution. In aluminosilicate glasses with 20–50 wt% Al2O3, the relative densities approached 90 % after CSP at 180 °C using a 10 M NaOH solution. Al(OH)3 formation in the cold-sintered glasses was confirmed, particularly at higher concentrations of NaOH solution (>10 M) and higher contents of Al2O3 (>40 wt%). Changes in Si structural units were observed during CSP, with Al-rich Si units becoming dominant as the concentration of the NaOH solution increased. The higher substitution of Si-O-Si bonds by Si-O-Al bonds led to the precipitation of Al(OH)3, as well as an increased Vickers hardness and biaxial flexural strength of the cold-sintered glasses. These findings demonstrate that the Al2O3 content and NaOH concentration play important roles in the densification and enhancement of the mechanical property in the cold-sintered alumina-rich binary aluminosilicate glasses and offer insights into the optimal conditions for obtaining desirable aluminosilicate materials through CSP.

Control of the grain structure and wear behavior of a Y2O3 nanoparticle dispersed Stellite 6 alloy fabricated by laser-directed energy deposition

A nuclear reactor is operated with load following that generates more wear than the base load; therefore, the wear resistance of the Stellite 6 alloy should be further improved. This study fabricated a wear-resistant oxide dispersion-strengthened (ODS) Co-based Stellite 6 alloy by varying the amount of Y2O3 nanoparticles (0, 0.6, and 1.5 wt%). The feedstocks for the ODS Stellite 6 alloy samples were prepared via mechanical mixing and radio frequency plasma spheroidization. The samples were then prepared by laser-directed energy deposition to obtain a finer grain structure with superior wear properties. In the ODS Stellite 6 alloy samples, the addition of nanoparticles changed the grain structure from columnar to equiaxed and refined the maximum grain size by 68.9 % compared with that of the Stellite 6 alloy sample. In addition, the nanoparticles were dispersed in the interdendritic region of the ODS Stellite 6 alloy samples. The nanoparticles formed a layer in front of dendritic grains and inhibited the movement of the grains and diffusion of solute atoms. As a result, the ODS Stellite 6 alloy samples had a small equiaxed grain structure. Furthermore, a high density of nanoparticles had an Orowan dispersion-strengthening effect. Therefore, the ODS Stellite 6 alloy samples exhibited a maximum increased Vickers hardness value of 15.9 % and maximum reduced specific wear rate of 58.2 % compared with those of the Stellite 6 alloy sample. Moreover, the ODS alloys exhibited superior wear behavior than Stellite 6 alloy because Y2O3 reinforcement prevents the ODS alloys from being easily abraded or plowed from counterpart material. This study indicates that the ODS Stellite 6 alloys with the optimal amount of Y2O3 nanoparticles dispersed control the grain structure and exhibit superior wear behavior compared with other reported Co-based alloys.

Study on structure and properties of La2O3–TiO2–B2O3 system glass

High refractive index La2O3–TiO2–B2O3 (LTB) system glasses have been successfully prepared by traditional melt-quenching method. Based on XPS results, we acquire details regarding the Ti oxidation state, coordination environments of boron and titanium, and the ratio of bridging to non-bridging oxygens within the glass. The predominant structural units identified in the glass matrix include [BO4], [BO3] and [TiO5] polyhedra, alongside a fraction of [TiO4] and [TiO6] polyhedra. The incorporation of TiO2 results in a reduction of the [BO4] tetrahedral groups and an increase of bridging oxygens and non-bridging oxygens bonds with Ti within the glass structure. 20 % of Ti(Ⅳ) ions in the glass are reduced to Ti(Ⅲ) ions. The addition of TiO2 content leads to an increase in Vickers hardness and refractive index of the glass, with [TiO5] polyhedra notably enhancing the refractive index. However, the increase in TiO2 content correspondingly decreases glass transmittance due to the charge transfer between Ti4+ or Ti3+and O2−.

High-temperature oxidation behavior of TA15 aerospace titanium alloy at 500 °C and 800 °C

This study investigates the high-temperature oxidation behavior and performance of TA15 Ti alloy subjected to 500 and 800 °C service conditions. The oxidation process, microstructural evolution, mechanical property changes, and comprehensive performance were analyzed. At 500 °C, the alloy developed a distinctive blue-colored surface primarily composed of Ti6O, indicating a slow growth rate of the oxide layer. In contrast, the 800 °C condition led to severe oxidation with notable TiO2 and Al2O3 phases and extensive peeling of the oxidation layer. Microstructural analysis revealed that at 500 °C, there was minimal surface oxidation, and the microstructure showed a shallow heat-affected zone. At 800 °C, repeated oxidation and peeling cycles resulted in grain growth and a significant decrease in the β-phase proportion. Mechanical property assessments indicated an increase in micro Vickers hardness at both temperatures, with the 800 °C sample exhibiting higher values. However, tensile strength decreased significantly at 800 °C due to the severe oxidation layer peeling, reducing the effective thickness during tensile testing. In summary, TA15 demonstrated good high-temperature service performance at 500 °C, while at 800 °C, severe oxidation and peeling adversely affected the overall performance. This research provides insights into the differential high-temperature behavior of TA15, crucial for applications in elevated temperature environments.

Effect of Nitrogen Atmosphere Annealing of Alloyed Powders on the Microstructure and Properties of ODS Ferritic Steels.

Oxide Dispersion Strengthened (ODS) ferritic steels are promising materials for the nuclear power sector. This paper presents the results of a study on the sintering process using the Spark Plasma Sintering (SPS) technique, focusing on ODS ferritic steel powders with different contents (0.3 and 0.6 vol.%) of Y2O3. The novelty lies in the analysis of the effect of pre-annealing treatment on powders previously prepared by mechanical alloying on the microstructure, mechanical, and thermal properties of the sinters. Using the SPS method, it was possible to obtain well-densified sinters with a relative density above 98%. Pre-annealing the powders resulted in an increase in the relative density of the sinters and a slight increase in their thermal conductivity. The use of low electron energies during SEM analysis allowed for a fairly good visualization of the reinforcing oxides uniformly dispersed in the matrix. Analysis of the Mössbauer spectroscopy results revealed that pre-annealing induces local atomic rearrangements within the solid solution. In addition, there was an additional spectral component, indicating the formation of a Cr-based paramagnetic phase. The ODS material with a higher Y2O3 content showed increased Vickers hardness values, as well as increased Young's modulus and nanohardness, as determined by nanoindentation tests.

Effects of Sinter-HIP Temperature on Microstructure and Properties of WC–12Co Produced Using Binder Jetting

This study investigates the influence of different sinter-HIP temperatures and binder saturation levels on the microstructure and properties of WC–12Co cemented carbide, produced using binder jetting. The sinter-HIP process was performed at 1400 °C, 1460 °C, and 1500 °C and binder saturation levels of 60% and 75% were selected during printing. The binder saturation proved to affect the repeatability of the manufacturing process and the sturdiness of the green models. The increase of the sintering temperature from 1400 °C to 1460 °C is correlated with an increase in the density. Nonetheless, a further raise in temperature to 1500 °C leads to significant grain coarsening without clear advantages in terms of porosity reduction. Both the transverse rupture strength and Vickers hardness increase when the sinter-HIP temperature rises from 1400 °C to 1460 °C, where the typical results for traditionally manufactured WC–12Co are met, with a comparable grain size. The transverse rupture strength and Vickers hardness then decrease for samples treated at 1500 °C. Finally, potential issues in the manufacturing process are identified and correlated with the defects in the final components.

Chemical ordering induced elastic hardening and thermoelastic properties of β phase Mg1-xScx lightweight shape memory alloys

The effect of chemical ordering on the thermoelastic properties of Mg-Sc light weight shape memory alloys are studied by the exact muffin-tinorbital method. Chemical ordering has significant hardening effect on elastic properties of Mg-Sc alloys, the C' is increased by 21% for Mg76Sc24 alloy, and the elastic hardening due to ordering can properly explain the increase in Vickers hardness observed in experiment. The quasi-harmonic Debye-Grüneisen model simulated the order–disorder transition temperature reasonably. The vibrational entropy increase due to elastic softening induced by disordering contributes considerably in driving the order–disorder transition. Mg-Sc alloys in ordered phase shows better thermoelastic stability over well-known commercial Mg alloys, therefore, ordering treatment of Mg-Sc are beneficial for structural application of this family of alloys. The Sc atoms (Mg atoms either) in bcc nearest neighboring lattice repel each other to form a B2-type ordered phase, and resultantly, the s-d and p-d hybridization between nearest neighboring Mg and Sc atoms is the main electronic reason for elastic hardening. The findings in current article not only give insight into understanding the strengthening mechanism during the ordering process of Mg-Sc alloys, but also provides a useful reference for the future development and modification of their shape memory effects.

Effects of TiB2 content on microstructural evolution, microhardness and tribological behaviours of Al matrix composites reinforced with TiB2 particles

In this study, Al2024/TiB2 composites with different TiB2 fractions (5, 10 and 15 vol%) were fabricated by high-energy ball milling and spark plasma sintering. The effects of TiB2 fraction on the microstructure, hardness and wear resistance of the composites were explored to determine the optimal TiB2 content in the composite with optimal properties. An increase in Vickers hardness of the composites correlates with the increased TiB2 content, and the Al2024-15TiB2 composite exhibits the highest hardness. The wear rate of the composite initially increases and then decreases with higher TiB2 content. Notably, the Al2024-10TiB2 composite demonstrates the best wear resistance with a wear rate of 1.14 × 10−4 mm³/Nm, representing a 96.81 % reduction compared to the unreinforced Al2024. The deteriorated wear resistance of the Al2024-15TiB2 composite was attributed to the decreased toughness and severe three-body abrasion caused by the excessive TiB2 particles.

Effect of Nb Addition on the Corrosion and Wear Resistance of Laser Clad AlCr2FeCoNi High-Entropy Alloy Coatings

Laser clad AlCr2FeCoNiNbx (x = 0, 0.5, 1.0, 1.5, 2.0, with x values in molar ratio) high-entropy alloy (HEA) coatings were fabricated on Q345 carbon steel. This study delves into the impact of Nb incorporation on the reciprocating sliding wear resistance of these laser clad coatings against a Φ6 mm silicon nitride ball. The microstructure of the as-clad AlCr2FeCoNiNbx coatings transformed from a single Face-Centered Cubic (FCC) solid solution (when x = 0) to the hypoeutectic state (when x = 0.5) and progressed to the hypereutectic state (when x ≥ 1.0). This evolution was marked by an increase in the Laves phase and a decrease in FCC. Consequently, the HEA coatings exhibited a gradually increasing Vickers hardness, reaching a peak at HV 820. Despite a decline in corrosion resistance, there was a notable enhancement in wear resistance, and the friction of the HEA coating could be reduced by Nb addition. The phase evolution induced by Nb addition led to a shift in the predominant wear mechanism from delamination wear to abrasive wear. The wear rate of Nb0.5 was impressively low, at 6.2 × 10−6 mm N−1 m−1 when reciprocating sliding under 20 N in air. In comparison to Nb0, Nb0.5 showcased 3.6, 7.2, and 6.5 times higher wear resistance at 5 N, 10 N, and 20 N, respectively. Under all applied loads, Nb1.5 has the lowest wear rate among all HEA coatings. This substantiates that the subtle introduction of Laves phase-forming elements to modulate hardness and oxidation ability proves to be an effective strategy for improving the wear resistance of HEA coatings.

Microstructure evolution of FD-POEM powders during high-temperature plasma spheroidization

The freeze–dry pulsated orifice ejection method (FD-POEM) can be coupled with plasma spheroidization (PS) as an advanced approach for fabricating spherical refractory powders used in laser additive manufacturing. However, the microstructure evolution of FD-POEM powders, which include components of various melting points, during ultrahigh-temperature PS treatment remains unclear. In this work, the morphology, chemical composition, and microstructure of MoSiBTiC alloy powders, as representative PS powders, were systematically investigated. The mesh-structured FD-POEM powders underwent complete densification, resulting in a 52 % reduction in particle size. The PS powders were composed of coarse solid solution Mo (Moss) and fine eutectic Mo5SiB2/TiC phases, consistent with the composition of additively manufactured MoSiBTiC alloys. With an increase in Si content, the volume fraction of fine Mo5SiB2 phases increased, resulting in increased Vickers hardness. Notably, the oxygen content of FD-POEM powders decreased by > 99 %, owing to the effective elimination of surface oxides on the initial elemental powders during ultrahigh-temperature PS treatment. This research provides an innovative approach for reducing the oxygen content in refractory powders to be used for additive manufacturing. Enhanced understanding of the microstructure evolution of PS powders can facilitate the composition optimization of refractory powders and development of a microstructure–property database for additively manufactured materials.

Phase Stability and Slag-Induced Destabilization in MnO2 and CeO2-Doped Calcia-Stabilized Zirconia.

MnO2 and CeO2 were doped to improve the corrosion resistance of CSZ (calcia-stabilized zirconia), and we studied the phase formation, mechanical properties, and corrosion resistance by molten mold flux. The volume fraction of the monoclinic phase gradually decreased as the amount of MnO2 doping increased. The splitting phenomenon of the t(101) peak was observed in 2Mn_CSZ, and in 4Mn_CSZ, it was completely split, forming a cubic phase. The relative density increased and the monoclinic phase decreased as the doping amount increased, leading to an increase in Vickers hardness and flexural strength. However, in 3Mn_CSZ and 4Mn_CSZ, where cubic phase formation occurred, the tetragonal phase decreased, leading to a reduction in these properties. MnO2-doped CSZ exhibited a larger fraction of the monoclinic phase compared to the original CSZ after the corrosion test, indicating worsened corrosion resistance. These results are attributed to the predominant presence of Mn3+ and Mn2+ forms, rather than the Mn4+ form, which has a smaller basicity difference with SiO2, and due to the low melting point. The monoclinic phase fraction decreased as the doping amount of CeO2 increased in CeO2-doped CSZ, but the rate of decrease was lower compared to MnO2-doped CSZ. The monoclinic phase decreased as the doping amount increased, but the Vickers hardness and flexural strength showed a decreasing trend due to the low relative density. The destabilization behavior of Ca in SEM-EDS images before and after corrosion was difficult to identify due to the presence of Ca in the slag, and the destabilization behavior of Ce due to slag after corrosion was not observed. In the XRD data of the specimen surface after the corrosion test, the fraction of the monoclinic phase increased compared to before the test but showed a lower monoclinic phase fraction compared to CSZ. It is believed that CeO2 has superior corrosion resistance compared to CaO because Ce predominantly exists in the form of Ce4+, which has a smaller difference in basicity within the zirconia lattice.

Improving the Mechanical and Electrochemical Performance of Additively Manufactured 8620 Low Alloy Steel via Boriding

In this study, mechanical and electrochemical performance of borided additively manufactured (AM) and wrought 8620 low alloy steel were investigated and compared to their bare counterparts. The microstructure of borided 8620 exhibited the presence of FeB and Fe2B phases with a saw tooth morphology. Both AM and wrought samples with boride layers showed a similar performance in hardness, wear, potentiodynamic polarization (PD), electrochemical impedance spectroscopy (EIS), and linear polarization resistance (LPR) experiments. However, borided steels exhibited about an 8-fold increase in Vickers hardness and about a 6-fold enhancement in wear resistance compared to bare ones. Electrochemical experiments of borided specimens (both AM and wrought) in 0.1 M Na2S2O3 + 1 M NH4Cl solution revealed a 3–6-fold lower corrosion current density, about a 6-fold higher charge transfer resistance, and about a 6-fold lower double-layer capacitance, demonstrating an improved corrosion resistance compared to their bare counterparts. Post-corrosion surface analysis revealed the presence of thick sulfide and oxide layers on the bare steels, whereas dispersed corrosion particles were observed on the borided samples. The enhanced wear and electrochemical performance of the borided steels were attributed to the hard FeB/Fe2B layers and the reduced amount of adsorbed sulfur on their surface.

Chemistry and microstructure of duplex stainless steel powders from recycled Z100 mixed with 316L steels

Recovered metallic waste can be used in additive manufacturing as a feedstock if the subsequent steps of the waste-to-product process are sufficiently mastered. In this study, impact of recycling of Z100 duplex steel mixed with 316L steel on the resulting powders microstructure and chemical composition was investigated. The utility of the original method of recycling stainless steels into a high-grade powder suitable for additive techniques has been demonstrated. By examining three gradations of powders, namely 20–50 μm, 50–100 μm and 125–250 μm, differences in selected properties in relation to the average particle size are shown. The results suggest that with increasing the particle diameter, fine-crystalline γ-austenite is favoured to precipitate at the boundaries and within the volume of the originally formed large δ-ferrite grains. It is reflected by a decrease of δ/γ fraction ratio from 0.64 in the 20–50 μm powders to 0.20 in the 125–250 μm, respectively. Obtained results indicate non-diffusional, shear or semi-shear character of δ → γ + δ phase transformation. The resulting fine-crystalline austenite is characterised by a significant dislocation density, which induces dislocation strengthening effect, responsible for an increase in Vickers hardness from 145 HV and Young's modulus from 29 GPa in the 20–50 μm group to 310 HV and 146 GPa in the 125–250 μm fraction, respectively.

Effect of Strain Rate on Deformation Behaviors of Ti-12.1Mo -1Fe Metastable Beta Alloy

The addition of expensive elements to β titanium alloys, which are widely used in the aerospace and automobile industries, causes their price to increase. Low-cost, high-strength alloy (Ti-12.1Mo-1.0Fe) was designed in this study and the compressive behaviors of this alloy were evaluated for application to automobile parts, etc. As a result of ambient compression in the quasi-static and dynamic strain rate range (1×10<sup>-4</sup>/s~6×10<sup>3</sup>/s), twinning occurred at all strain rates, and in particular, adiabatic shear bands were observed, which cause cracks and fractures under dynamic strain rate conditions. In addition, when the relationship between these bands and mechanical characteristics was evaluated, an increase of compression strength and Vickers hardness was confirmed to occur, due to the strain rate hardening effect under compression loading. Some twins were formed by the deformation behavior during compression plastic deformation of the Ti-12.1Mo-1.0Fe alloy, and it exhibited excellent compression strength characteristics, showing a very high strain rate hardening effect at a high strain rate.

Phase Formation and Stabilization Behavior of Ca-PSZ by Post-Heat Treatment II: CaOx-ZrO2(1 − x) (x = 5–10 mol%)

The effects of CaO content and post-heat treatment were investigated on the phase stability and mechanical and thermal properties of Ca-PSZ. ZrO2 specimens with 5–10 mol% CaO were sintered, and post-heat treatment was performed at 1200 °C for 100 h. Subsequently, to test and analyze the crystal structure and the microstructure, the mechanical and thermal properties of the specimens were evaluated. All specimens were partially stabilized by 5–10 mol% CaO (5CSZ–10CSZ) in a mixed monoclinic and tetragonal phase; however, peaks of the secondary phase of CaZrO3 were observed in 10CSZ. The ratio of the monoclinic phase decreased from 62.50% (5CSZ) to 21.02% (10CSZ) as the CaO content increased. Additionally, the monoclinic phase ratio decreased from 59.38% (5CSZ) to 19.57% (9CSZ) after the post-heat treatment; an increase to 24.84% was observed for 10CSZ. An increase in Vickers hardness from 676.02 to 1256.25 HV and flexural strength from 437.7 to 842.7 MPa was observed with increasing CaO content. The post-heat treatment resulted in further increases in these values as the CaO content increased from 5CSZ to 9CSZ; however, the Vickers hardness and flexural strength of 10CSZ decreased by approximately 8% and 9%, respectively. The thermal expansion coefficient exhibited the same tendency as the mechanical properties. This coefficient increased from 8.229 × 10−6 to 9.448 × 10−6 K−1 with increasing CaO content and was enhanced after the post-heat treatment in 5CSZ to 9CSZ; however, the thermal expansion coefficient of 10CSZ decreased by approximately 4% after the post-heat treatment. The mechanically and thermally stable tetragonal phase increased, and the monoclinic phase decreased as the doped Ca replaced the Zr sites, as was confirmed by the X-ray diffraction (XRD) analysis. The post-heat treatment and the increased Ca addition further facilitated the replacement of Zr sites by Ca. However, at high Ca concentrations of 10CSZ, an equilibrium phase of CaZrO3 was formed as a secondary phase at the post-heat treatment temperature, resulting in low performance.

Infrared irradiation to drive phosphate condensation as a route to direct additive manufacturing of oxide ceramics

AbstractThis paper introduces a fast, low‐temperature, pressureless process to chemically bind ceramic parts with the help of infrared (IR) irradiation and phosphate binder condensation. Ceramic components are synthesized from slurries of ceramic powders and Al(H2PO4)3 binder that are irradiated with short‐waved IR light capable of heating the system to 350°C. This irradiation is found to be sufficient to drive phosphate condensation, binding the ceramic powders together within a matter of seconds. The IR‐irradiated components show an increase in density and Vickers hardness. Layer‐by‐layer spraying and irradiation is demonstrated as a route to additive manufacturing using various ceramic chemistries. While further optimization is needed to control desired microstructure, this process of using chemically bonded ceramic binders with IR heating for additive manufacturing shows the potential to find applications in various ceramic systems, including refractories, bone implants, electronics, and thermal barrier coatings.

Mechanical Properties of Nano SiC Reinforced Aluminum 7075-T6 Produced by Warm Powder Compaction using an Inert Gas

The micron-sized Al7075powder reinforced with nano-sized SiC particles is compacted at 4000C in an inert atmosphere using Nitrogen. It is shown that this technique can significantly improve the mechanical properties of the compacted powder characterized by measuring hardness, stress-strain curves and density. The maximum relative density was %98.8 and obtained for 2.3 GPa pressure and 0%SiC content. The minimum density was %93.95 and was obtained for 10%SiC content and 1.3 GPa pressure. The degree of porosity and the number and size of the void decreased as the compaction pressure increased and increased with the increase of SiC volume fraction. The maximum increase in ultimate strength was about 72% and occurred for the 5%SiC content and the 1.3 GPa compaction pressure. For 10%SiC volume fraction the strength improved by 53% for 2.6 GPa pressure. The effect of SiC content on ultimate strength was significantly higher than that of the compaction pressure. The maximum increase in Vickers hardness of the compacts was 100% and obtained for the samples with 10%SiC volume fraction and compacted at 2.6 GPa pressure. Again, the effect of SiC volume fraction on hardness improvement was found to be remarkably greater than that of compaction pressure.

Construction of FeCrVTiMox high-entropy alloys with enhanced mechanical properties based on electronegativity difference regulation strategy

The development of high-entropy alloys (HEAs) as coating materials for protecting cutting tools remains a big challenge due to the diversity of their compositions and structures. In this work, we demonstrated an electronegativity regulation strategy to improve the mechanical properties of FeCrVTiMox HEAs coatings by introducing the high-electronegativity Mo element, which has been confirmed to be effective both in theoretical calculations and experimental studies. Thermodynamic analysis and the first-principles calculations predicted that FeCrVTiMox could readily form a single solid solution with a body-centered cubic (BCC) phase, and the electronegativity difference with increased Mo content showed a linear correlation for the improved mechanical properties of HEAs. The FeCrVTiMox HEA coatings synthesized using the laser cladding technique exhibited the increased Young's modulus from 227.8 GPa to 251.6 GPa, the increased Vickers hardness from 2.15 GPa to 8.19 GPa, and in the decreased frictional wear weight loss from 1.14 mg to 0.18 mg, supporting the predictions. The microscopic mechanism of solid solution strengthening of Mo elements was analyzed by Density of states (DOS) and electron localization function (ELF). The d‐orbital electron of each metal atom hybridizes with one another, leading to that Mo element with high electronegativity can attract and localize electrons to form covalent bonds. The larger electronegativity difference is, the more covalent bonds can be formed, in turn enhancing the mechanical properties of HEAs.