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The eutectic high entropy alloys with large amounts of Al and Cr have exhibited superior oxidation resistance. Here, we confirmed that Si could further enhance the oxidation resistance by forming a continuous oxidation layer in Fe36Ni36Al15Cr10Si2Mo1 alloy. Si promoted the outward diffusion and transformation of Al which effectively enhanced the oxidation resistance. The FeCr2O4 spinel and silicate formed by the solid-state reaction also contributed to the oxidation resistance. The thermodynamic and kinetic factors were then discussed to understand the inherent oxidation mechanism of the dual-phase Fe36Ni36Al15Cr10Si2Mo1 alloy, which provide new insights into the dual-phase alloy design and oxidation resistance. [ABSTRACT FROM AUTHOR]

AlCrFeNi multi-component alloys with excellent mechanical properties have been designed and extensively investigated in recent years. The massive fabrication of sheets will be an effective way for industrial application, where hot rolling is the inevitable process. After hot rolling, the mechanical properties could be further tailored. In this study, the effects of heat treatments on a dual-phase Al17Cr10Fe36Ni36Mo1 hot-rolled plate were systematically investigated, including: (i) annealing (700 °C, 850 °C, 1000 °C and 1150 °C for 1 h, respectively), (ii) solution and single aging (1150 °C for 1 h and 700 °C for 4 h), (iii) solution and double aging (1150 °C for 1 h, 700 °C for 4 h and 650 °C for 1 h). The B2 precipitates with varied morphologies were observed in the FCC matrix of the hot-rolled alloy after a heat treatment range from 700 °C to 1000 °C for 1 h, and the BCC particles in the B2 matrix were dissolved when the heat treatment temperature was higher than 1000 °C. The hot-rolled alloy heat treated at 700 °C for 1 h had the highest yield strength, and the hot-rolled alloy treated at 1150 °C for 1 h showed the lowest yield strength. After a solution at 1150 °C for 1 h, aging at 700 °C for 4 h and 650 °C for 1 h, the L12 phase and BCC particles were precipitated in the FCC and B2 matrices, and B2 nanoprecipitates were observed around the FCC grain boundaries. The solution and double aging alloy exhibit the tensile strength of 1365.7 ± 9.5 MPa, a fracture elongation of 14.2 ± 1.5% at 20 °C, a tensile strength of 641.4 ± 6.0 MPa, and a fracture elongation of 16.9 ± 1.0% at 700 °C, showing great potential for application. [ABSTRACT FROM AUTHOR]

The metastable-stable transition and rapid coarsening of metastable D022 phase remains its Achilles hell, restricting the application of D022-strengthened alloys at service temperatures higher than 650°C. Hence, it is crucial to improve thermal stability of D022 phase. In this work, we report an 800°C-stable D022-Ni3(W0.24Ti0.38Ta0.19Nb0.19) superlattice in the Ni58Cr23Fe10W5Ti2Ta1Nb1 MEA. Experimental results and theoretical analysis showed that the exceptional thermal stability is due to Nb-sublattice occupying elements, low diffusivity of W, and extremely small lattice misfit between the D022 phase and FCC matrix. These findings shed lights on developing high-performance D022-hardened alloys capable of operating at temperatures above 650°C. [ABSTRACT FROM AUTHOR]

Dual-phase high-entropy alloys with excellent room temperature and high-temperature properties have been widely studied as potential high-temperature structural materials. However, interface weakening causes its high-temperature performance to decline at higher temperatures, severely limiting further development. In this study, a series of Al17Cr10Fe36Ni36Mo1Hfx (x = 0, 0.03, 0.15, 0.3, 0.5, and 0.8 at%) alloys were prepared to study the effect of Hf content on the microstructure and mechanical properties of the matrix alloy. The results indicate that with the addition of the Hf, the Hf-rich phase began to precipitate at the interface and inside the B2 phase in the matrix alloy. In contrast, the morphology of both the FCC and B2 phases had no noticeable change. With the increase in Hf content, the high-temperature strength and ductility of the alloy first increased and then decreased, while the room temperature performance remained almost unchanged. Benefiting from the hindrance of the Hf-rich phase to grain boundary sliding and dislocation movement during high-temperature deformation, the tensile strength, yield strength, and plasticity of the matrix alloy increased from 474 MPa, 535 MPa, and 8.7% to 816 MPa, 923 MPa, and 42.0% for the Al17Cr10Fe36Ni36Mo1Hf0.5 alloys, respectively. This work provides a new path for designing a high-entropy alloy with excellent high-temperature mechanical properties. [ABSTRACT FROM AUTHOR]

This study aims to investigate a novel spraying technology. The spraying technology is named stud spraying since it has been developed by improving the traditional stud-welding process. Al–Cu coatings have been prepared on the surface of copper plates by using aluminium studs with bosses, and the thickness of the coating centre can be 15–30 μm under the height of stud boss (0.2 mm). The microstructure, phase structure and composition of the coating are characterized. The results show that a large number of Al–Cu intermetallic compounds and a few oxides are present in the coating. Numerous growth crystals are present at the metal interface between the coatings and the copper plate. The crystal morphology of the interface metal is growing from the copper plate to the coating metal which has also been enhanced the coating interface. The stud-coating process is a rapidly cooling solidification process that a variety of intermetallic compounds including θ phase (Al2Cu), η2 phase (Al48Cu52), ζ2 phase (Al9Cu11) and γ2 phase (Al4Cu9) are present within the layers. In addition, multiphase intermetallic compounds enhanced the surface microhardness of the coating with its value increasing from 85 to 222 HV. [ABSTRACT FROM AUTHOR]

The resource utilization and stabilization disposal of stainless steel pickling sludge has received more and more attention from domestic and foreign scholars. Here, a sustainable treatment process of low-silica reduction smelting for stainless steel pickling sludge, followed by low-temperature vitrification for the reduced slag, has been proposed. The metal yield can reach more than 98% and metal content in the slag is lower than 0.6% under the optimal conditions of 1400 C temperature, 15% coal ratio, 10% SiO2 addition, and 1.5 h reaction time. The distinguishable crystal phase in the alloy mainly contained FeNi intermetallic compounds. The reduced slag mainly consisted of fluorite, anorthite, and magnesium silicate. The vitrification experiments implied that it was conducive to increase the vitreous body content of reduced slag via lowering the temperature. The vitreous body content of vitrification products can reach more than 85% when the SiO2 addition is in the range of 10–20% at 1250°C. This work puts forward a new perspective to achieve both the recovery of valuable metals and the reduction of the slag amount. [ABSTRACT FROM AUTHOR]

Excellent ductility is crucial not only for shaping but also for strengthening metals and alloys. The ever most widely used eutectic alloys are suffering from the limited ductility and losing competitiveness among advanced structural materials. Here we report a distinctive concept of phase-selective recrystallization to overcome this challenge for eutectic alloys by triggering the strain hardening capacity of the duplex phases completely. We manipulate the strain partitioning behavior of the two phases in a eutectic high-entropy alloy (EHEA) to obtain the phase-selectively recrystallized microstructure with a fully recrystallized soft phase embedded in the skeleton of a hard phase. The resulting microstructure fully releases the strain hardening capacity in EHEA by eliminating the weak boundaries. Our phase-selectively recrystallized EHEA achieves a high ductility of ∼35% uniform elongation with true stress of ∼2 GPa. This concept is universal for various duplex alloys with soft and hard phases and opens new frontiers for traditional eutectic alloys as high-strength metallic materials. The ever most widely used eutectic alloys often suffer from limited ductility. Here the authors propose a distinctive concept of phase-selective recrystallization to significantly improve their ductility and strength and pave the way for new applications of the widespread eutectic alloys. [ABSTRACT FROM AUTHOR]

Recrystallization has been a major method to induce heterogeneous grain structure for improving the strength–ductility combination of single-phase high-entropy alloys (HEAs). However, the recrystallization kinetics, which are the guideline for controlling the recrystallization behavior, of single-phase HEAs are relatively less explored. Here, we uncover the recrystallization behaviors of typical single-phase NiCoCrFe and Ni2CoCrFe HEAs. Our results showed that the two investigated HEAs exhibit almost similar recrystallization activation energy around 230 kJ·mol−1, but distinctively different recrystallization kinetics. This abnormal difference is attributed to the deformation twins of NiCoCrFe. These findings indicate that, except for textbook factors, deformation twinning significantly enhances the recrystallization behavior of HEAs. [ABSTRACT FROM AUTHOR]

This paper investigates the difference in the corrosion resistance and passive property of CoCrNi medium-entropy alloy and 316 L stainless steel in a simulated marine environment by using electrochemical measurements, immersion test and surface analysis technology. The results reveal that CoCrNi MEA has more superior anti-corrosion resistance than that of 316 L. The difference in the corrosion resistance is related to the microstructure and surface passive film. Due to the presence of oxide inclusion, micro-galvanic corrosion is formed between the oxide inclusion and CoCrNi matrix, which promotes the anodic dissolution of CoCrNi MEA and induces the formation of pits. The matrix as the anode mainly undergoes the selective dissolution of Co element, while the selective dissolution of Co and Ni elements is occurred in the cathodic oxide inclusion. [Display omitted] • In 3.5%NaCl solution, the corrosion resistance of CoCrNi MEA is better than that of 316 L. • Anti-corrosion property of MEA and 316 L is associated with grain size, oxide and passive film. • Micro-galvanic corrosion effect between oxide and matrix facilitates the corrosion of MEA. • Pits on MEA are mainly attributed to the dissolution of Co element. • Inclusion as cathode occurs the selective dissolution of Co and Ni elements. [ABSTRACT FROM AUTHOR]

High entropy alloys (HEAs) with grain-scale heterogeneous structure and coherent precipitates have shown gigapascal strength and considerable ductility. However, the origins of the excellent ductility of the HEAs with both precipitates and grain-scale heterogeneous structures are relatively less explored and not well understood. It is also still challenging to obtain such precipitated heterogeneous HEAs through efficient and economical thermomechanical processing procedures. Here, through single-step heat treatment, we developed a Ni 2 CoCrFeTi 0.24 Al 0.2 HEA with an excellent yield strength of ~1.3 GPa and tensile elongation of ~20%. Using multiple length-scale microstructure characterizations and micro-digital image correlation analysis, we revealed the strengthening and toughening mechanisms of the novel HEA. Our results showed that the grain-scale heterogeneous structure with L1 2 precipitates ranging from ~10 to 100 nm is responsible for the excellent strength-ductility combination. The good ductility is attributed to the strain-partitioning-induced additional deformation modes, i.e., deformation twinning and microbands, as well as the efficient hetero-deformation induced strain hardening effect. The superior yield strength is mainly due to the effective combination of precipitation hardening and dislocation strengthening. These findings not only provide a facile route to develop strong and ductile alloys but also deepen the understanding of the deformation mechanism of hetero-structured materials. • A precipitated heterogenous HEA with yield strength of ~1.3 GPa and tensile elongation of ~20% was developed. • The heterogenous structure and coherent precipitates were obtained within the same single-step heat treatment. • The excellent ductility was attributed to additional deformation modes, i.e. deformation twins and micro-bands, and HDI strain hardening. • With the aid of micro-DIC analysis, strain partitioning was asserted to be the intrinsic origin of the interesting deformation mechanism. • Effective combination of precipitation hardening and dislocation strengthening is the main reason for high yield strength. [ABSTRACT FROM AUTHOR]

The recently emerged CoCrNi-based medium-entropy alloys (MEAs)/high-entropy alloys (HEAs) have a good combination of high strength and ductility. However, there are still challenges for further increasing their mechanical properties by finding optimal composition with simple processing. In this investigation, we revisited the commercial superalloys MP35N and MP159 with similar composition and entropy to CoCrNi-based MEAs/HEAs to find inspirations for designing CoCrNi-based MEAs. After a simple thermomechanical process, MP35N/MP159 can achieve a high tensile strength over 2.2 GPa at ambient temperature, better than a majority of present CoCrNi-based MEAs/HEAs. At intermediate temperature tensile tests, the aged MP159 also has a considerable tensile strength (1.8 GPa) and tensile elongation (12.5%). The underlying strengthening factors of aged MP35N/MP159 were investigated by transmission electron microscope. It indicated that precipitation strengthening, solid solution strengthening, and work-hardening could be introduced in CoCrNi-based MEAs through alloying, and simple thermomechanical treatments to significantly improve the performance. The present findings and perspectives provide useful enlightenment for developing ultra-strong CoCrNi-based MEAs/HEAs. ● The compositions of MP35N and MP159 are similar to CoCrNi-based MEAs/HEAs, and the configurational entropy already falls in the range of MEAs/HEAs. ● At ambient temperature, both MP35N and MP159 have a tensile strength of 2.2 GPa, better than a majority of CoCrNi-based MEAs/HEAs. ● Precipitation strengthening, solid solution strengthening, and work-hardening can be introduced in CoCrNi MEAs easily through alloying and simple thermomechanical treatments. [ABSTRACT FROM AUTHOR]

Refractory high-entropy alloys (RHEAs) have attracted considerable interest due to their elevated melting points and remarkable softening resistance. Nevertheless, the ambient-temperature brittleness and inadequate high-temperature oxidation resistance commonly limit the application of the body-centered-cubic (BCC) RHEAs. In this study, we achieved a Ti 41 V 27 Hf 11.5 Nb 11.5 Cr 3 Al 6 RHEA with a desirable yield strength of ∼1178 MPa and tensile ductility of ∼19.5 %. Exploring the underlying mechanisms, we demonstrated that Cr and Al alloying induced a nanoscale spinodal structure and generated a significant lattice misfit, resulting in a notable strengthening effect and pinning behavior. Meanwhile, dislocation configurations involving loops and cross slips were stimulated by pinning, serving a reliable strain-hardening capability to large strains. Significantly, Cr and Al alloying improved oxidation resistance and prevented severe spallation at high temperatures by forming protective oxide layers. These results provide opportunities to design novel RHEAs. [Display omitted] [ABSTRACT FROM AUTHOR]

The eutectic high-entropy alloys have shown promising mechanical behaviors while their softening at elevated temperatures is still a challenge. Generally, the boundaries are the weak parts to be strengthened with increased temperatures in eutectic high-entropy alloys. Here, we found that the minor addition of boron in Ni 30 Co 30 Cr 10 Fe 10 Al 18 W 2 eutectic high-entropy alloy can significantly strengthen the FCC grain boundaries and the FCC/B2 phase boundaries at elevated temperatures. A remarkable tensile yield strength over 581 MPa with elongation of 71 % at 800 °C is achieved with minor boron addition, corresponding to a 45 % increase in yield strength and 129 % improvement in ductility compared with the boron-free counterpart. Accompanied by the boron-strengthened phase boundary, sustainable dynamic recovery occurs in the FCC and B2 phases during high-temperature tensile testing, ensuring excellent ductility. Moreover, the benchmark test indicates that the strengthening effect of boron and borides on the boundaries contributes up to 166 MPa to the yield strength of eutectic high-entropy alloy at 800 °C. These findings shed light on the development of high-temperature eutectic high-entropy alloys with a microalloying strategy. [Display omitted] [ABSTRACT FROM AUTHOR]

• Phase-selective recrystallization and aging was applied to the FeNiCrAl alloy. • Effect of aging on the microstructure and mechanical properties were studied. • The tensile elongation significantly increases via phase-selective recrystallization. • The aged alloy shows ultimate strength of 1369.0 MPa and elongation of 23.0%. Phase-selective recrystallization process has been confirmed as an effective way to improve the ductility of dual-phase alloys. Here, the tensile property of a low-cost dual-phase Fe 37 Ni 36 Cr 10 Al 17 alloy was significantly improved via phase-selective recrystallization and aging. The equiaxed microstructure was obtained after phase-selective recrystallization and the tensile elongation significantly increases compared with as-cast alloy. Furthermore, the tensile strength increased to 1369.0 MPa and elongation increased to 23.0% by aging. The comprehensive property shows great potential applications for industrial prospects. [ABSTRACT FROM AUTHOR]

Multi-component alloys with good mechanical properties and casting liquidity have become a hotspot in the materials field. Typically, the addition of minor metal elements plays a vital role in strengthening the mechanical properties. However, doping metalloid elements such as Si into multi-component alloys is also an effective method to enhance the mechanical properties. In the present study, the effect of Si (0 ∼ 4 at%) on the microstructure and mechanical properties was investigated within both as-cast and thermal mechanical treatment states. In as-cast state, all 4 alloys exhibited dendrites and interdendrites structure. The fine structure enhanced tensile strength for Si1 and improved ductility for Si2. Once the Si content reached 4 at%, both the strength and ductility dropped dramatically. Phase selective recrystallization and aging greatly increased the tensile strength and ductility simultaneously. The alloys with addition of Si had similar mechanical properties after thermal mechanical treatment process. Si2 after recrystallization and aging was considered a promising candidate for further application with a yield strength of 960 MPa, tensile strength of 1463 MPa and fracture strain of 20.5%. This work provided a new prospect to design multi-component alloys with nonmetallic elements, which may be applied to wear, corrosion and oxidation resistance fields. • The effects of metalloid Si on the microstructure and mechanical properties of Fe 36 Ni 36 Cr 10 Mo 1 Al 17−X Si X was investigated. • The addition of Si enhanced tensile strength to 1305 MPa for Si1 and improved ductility to 24.8% elongation for Si2. • Si2-R-A showed mechanical properties with yield strength of 960 MPa, tensile strength of 1463 MPa and ductility of 20.5%. [ABSTRACT FROM AUTHOR]

High entropy alloys (HEAs) with D0 22 superlattice have shown excellent yield strength. However, long-time annealing leads to the decrease of strength due to the coarsening of D0 22 superlattice. Therefore, stabilizing the D0 22 phase of HEAs is of critical importance. Here, we report that a minor addition of Mo significantly enhances the phase stability of D0 22 phase and mechanical performance of Ni 2.1 CoCrFeNb 0.2 HEAs. Experimental results show that the Mo-doping slows down the coarsening of D0 22 phase significantly by decreasing the diffusivity and reducing the lattice misfit between precipitates and matrix. Due to the enhanced coarsening resistance of D0 22 phase, the Mo-doped Ni 2.1 CoCrFeNb 0.2 HEA shows good strength and ductility after long-term aging. These insights provide some guidelines for the design of precipitation-hardened alloys for high-temperature application. [ABSTRACT FROM AUTHOR]

The W and Mo are in the same groups of periodic table and are usually used as solid solution elements. In this investigation, the minor alloying behaviors of W and Mo in Fe 37 Ni 36 Al 17 Cr 10 alloy were explored. The addition does not change the casting microstructure greatly, with dendrite region of FCC + B2 and inter-dendrite region of FCC phase. For tensile properties at ambient temperature, as-cast Fe 36 Ni 36 Al 17 Cr 10 Mo 1 alloy exhibited higher yield strength and fracture strength compared with Fe 37 Ni 36 Al 17 Cr 10 alloy. Then, dual-phase alloys with Mo content of 2 and 3 at% were further designed and carefully studied. It is found that a nano-scale structure occurred in as-cast Fe 35 Ni 36 Al 17 Cr 10 Mo 2 alloy, where a large number of spherical BCC precipitates are distributed in the dendrite region of B2 phase. Meanwhile a mixture of irregular B2 phase and FCC phase is contributed to the inter-dendrite area. The Fe 35 Ni 36 Al 17 Cr 10 Mo 2 alloy exhibited the most excellent and comprehensive mechanical properties due to the fine structure and its high work hardening ability. The yield strength, ultimate tensile strength and fracture elongation of as-cast Fe 35 Ni 36 Al 17 Cr 10 Mo 2 alloy are 863 ± 20 MPa, 1285 ± 17 MPa and 16.0 ± 1.0 %, respectively, which is higher than the most of reported dual-phase as-cast FeNiCrAl multi-component alloys. • The alloying behaviors of W and Mo in Fe 37 Ni 36 Al 17 Cr 10 alloy were explored. • Effect of Mo amount on the microstructure and mechanical properties were studied. • A nano-scale structure consisted of FCC, B2 and BCC occurred in as-cast alloy. • The Fe 35 Ni 36 Al 17 Cr 10 Mo 2 alloy exhibited the most excellent mechanical properties. [ABSTRACT FROM AUTHOR]

Face-centered-cubic (FCC) Multi-principal element alloys (MPEAs) have attracted intensive scientific research interest due to their excellent fracture toughness and ductility. Still, the strengths of single-phase MPEAs are unsatisfactory. Although great progress has been made by utilizing multiple strengthening mechanisms, it remains challenging to take advantage of large-atom solutes and nano-precipitates simultaneously because solutes always partition into the precipitates. In the present work, we successfully achieved an effective combination of solid solution strengthening and precipitation hardening in the NiCrFeWTiAl multi-principal element alloys. Our experimental results showed that W is partitioned into the FCC matrix, while Ti and Al tend to exist in the L1 2 phase. This controlled elemental partitioning leads to a good combination of solid solution strengthening and precipitation hardening effects and results in good tensile properties at temperatures from 25 ℃ to 760 ℃. The strengthening mechanisms were revealed based on the quantified microstructure analysis. The solid solution hardening of all the solute atoms contributes ∼140 MPa in total, but W mainly contributes to solid solution hardening, and L1 2 precipitates enhance the yield strength by ∼330 MPa through ordering strengthening. • The NiCrFeWTiAl MPEAs efficiently combine the solid solution strengthening and precipitation hardening. • The W partitioned into the FCC matrix mainly leads to solid solution hardening. • The L1 2 phase which enriched in Ti and Al enhances the yield strength through the ordering strengthening mechanism. • The effect of Cr on the microstructure and mechanical properties was demonstrated. [ABSTRACT FROM AUTHOR]

Precipitation hardening is used as a powerful strengthening pathway to tailor the mechanical properties of traditional alloys. However, in refractory multi-principal element alloys (RMPEAs), the precipitates with remarkable strengthening effect are relatively less explored. Here, we report novel precipitation hardened body-centered-cubic (BCC) TiVNb RMPEAs through doping surplus boron. 2000 ppm (0.2 wt%) boron doping leads to TiB precipitates, which can enhance the yield strength of TiVNb by ∼350 MPa. Orowan strengthening caused by TiB precipitates serves as the primary strengthening mechanism compared to non-boron alloys. Due to boron doping, the dislocation-mediated deformation transfers from planar-slip to cross-slip and thus avoids stress concentration caused by high-density geometrically necessary dislocation. The excellent strengthening effect and tuned deformation mechanisms led to an optimal RMPEA with a yield tensile strength of ∼972 MPa and an elongation of ∼12%. This work demonstrates that TiB is an efficient precipitate in BCC RMPEAs, which is constructive for the development of precipitation hardened RMPEAs. [Display omitted] • Surplus boron doping is put forward to produce stable TiB precipitates in the TiVNb alloy. • Nanoscale TiB precipitates can increase the yield tensile strength by 35.7% via Orowan strengthening. • The cross slip in the TiVNbB RMPEA led to an undamaged elongation of ∼12%. [ABSTRACT FROM AUTHOR]

It is still a challenge to further increase the yield strength of eutectic high-entropy alloys, a promising multiple principal alloy system. By modifying the Ni: Co ratio to introduce the γ′ phase, we developed a series of Ni 60-x Co x Cr 10 Fe 10 Al 18 Mo 2 (x = 30, 20, 10, 0) casting hypoeutectic high-entropy alloys with improved yield strength and ductility. The increase of Ni concentration via decreasing Co concentration promotes the amount of FCC phase with nano γ′ particles in it. The as-cast Ni 60 Cr 10 Fe 10 Al 18 Mo 2 HEA with FCC/γ'+B2 phase composition exhibits a superior σ 0.2 –831 MPa due to the formation of the γ′ phase. The results provide a feasible route for developing high-performance Ni–Co–Cr–Fe–Al casting HEAs with multiscale microstructure. [ABSTRACT FROM AUTHOR]

The large amounts of data in eutectic high-entropy alloys (EHEAs) provide the opportunity for a rapid design of superior high-entropy alloys (HEAs). In this letter, we proposed a strategy to screen high-performance supersaturated HEAs based on the existing EHEAs with superior properties. The designed HEAs of supersaturated terminal solid solutions possess unique characteristics. On the one hand, the as-cast alloys exhibited primary single-phase dendrites/grains with maximum solid solution hardening and minor interdendritic/intergranular second phases as modifiers. On the other hand, the maximum saturation enabled the highest volume fraction of precipitates during aging. Taking advantage of these characteristics, high strength and ductility were achieved in the designed HEAs. These findings can accelerate the exploration of supersaturated HEAs with superior properties. [Display omitted] [ABSTRACT FROM AUTHOR]

• Effects of pre-strain on precipitation kinetics and strengthening mechanisms of γ'-strengthened HEAs were studied. • Pre-strain can accelerate precipitation kinetics but shows a non-monotonous feature with the increase of pre-strain. • The shortened defects existing time by recrystallization can weaken the acceleration effect at high pre-strain. • Strengthening mechanisms can be tuned by different pre-strain to realize targeted properties. Pre-strain is often used as a powerful pre-treatment to tailor the microstructures and mechanical properties of traditional alloys. However, in high-entropy alloys (HEAs), the effect of pre-strain degree on the precipitates is still unclear. In this paper, we investigated the effects of pre-strain degree on the precipitation of Ni 2 CoCrFeTi 0.18 Al 0.12 high-entropy alloys. The HEAs were cold-rolled with different thickness reduction of 30%, 50%, and 70% and annealed at 800 °C for 30 ~ 60 min, followed by high-resolution scanning electron microscope (SEM) analysis. Counter-intuitively, we discovered a non-monotonous effect of pre-strain on the precipitation behavior, that low pre-strain can accelerate the precipitation behavior while such accelerating effect is weakened under high pre-strain. This non-monotonous effect is attributed to the shortened defects existing time by recrystallization under high pre-strain. In addition, pre-strain can controllably tailor the precipitation strengthening, dislocation strengthening, and grain boundary strengthening of HEAs. These results not only uncover the mechanism of the non-monotonous pre-strain effect on the precipitates but also provides a pre-strain mediated scheme for tuning the precipitation-strengthened HEAs to targeted properties. [ABSTRACT FROM AUTHOR]

Single-phase concentrated solid-solution alloys (SP-CSSAs) have shown great potential as structural materials in advanced reactor systems. Up to date, nevertheless, the synergistic effect of compositional complexity and irradiation temperature on helium (He) irradiation-induced cavity formation has not been systematically studied yet. In this work, pure Ni and three prototype face-centered-cubic SP-CSSAs, i.e., NiCo, NiCoCr and NiCoFeCrMn, were irradiated with He+ ions at 673, 773, 873 and 973 K. The evolution of He-induced cavities were investigated in detail with transmission electron microscopy. It was found that growth of He cavities was suppressed with increasing compositional complexity at 673 and 773 K. Due to the lower melting temperature, NiCoFeCrMn exhibited the strongest temperature susceptibility in terms of He cavity growth with the increasing temperature. Interestingly, the He cavity growth tended to be enhanced with increasing compositional complexity when the radiation temperature increaseed to 973 K, which can be attributed to the prominent chemical-biased vacancy migration at high temperatures. [ABSTRACT FROM AUTHOR]