Excellent activation and high capacity qualify the A5B19-type RE-Mg-Ni-based hydrogen storage alloy as anode material for nickel/metal hydride batteries. Its cycling stability, however, is insufficient to satisfy industrial standards. Herein, phase transformation was studied in a consecutive temperature-rising process, and a Pr5Co19-type La-Y-Mg-Ni-Al-based alloy was achieved at 1030 degrees C. The subsequent electrochemical measurements show that the multiphase alloy with more phase interfaces has strikingly high-rate discharge ability performance and low temperature performance. At a discharge current density of 2160 mA/g, the discharge capacity is still 68.3% of the fully-discharged capacity, and the discharge capacity maintains up to 240.5 mAh/g at -40 degrees C. Otherwise, the single-phase Pr5Co19-type alloy has superior cycling performance. After 200 cycles of charge and discharge, the capacity retention rate is as high as 80.2%. Structural evolution analysis reveals the degradation mechanism of single-phase Pr5Co19-type alloy, and it is found that the mismatch between [AB5]-1 and [AB5]-2 subunits may be the main factor causing capacity degradation. This work provides new insight into understanding the degradation of Pr5Co19-type superlattice alloys. (c) 2024 Chinese Society of Rare Earths. Published by Elsevier B.V. All rights are reserved, including those for text and data mining, AI training, and similar technologies.

Fiber-reinforced polymer composites are prone to cure deformation issues after manufacturing, which directly affects their engineering applications. To effectively control the deformation issues of composite laminates during the manufacturing process, this study focuses on glass fiber/epoxy composites, using asymmetric [90 5 /0 5 ] laminates to explore how temperature cycles and cure pressure impact deformation. The experimental results indicate that in the two-stage heating cycle, controlling the holding time in the first stage to cure the composite material to a state near the glass transition can more effectively reduce deformation. Compared to the standard temperature cycle, this temperature cycle can reduce the end deflection of the laminate by approximately 15.9%. Due to the inhibitory effect of pressure, when the cure pressure is increased from 0 MPa to 8 MPa, the end deflection of the laminate decreases by 59.4%. However, pressure introduces residual stress inside the material and retains this stress in a locked state within the material. The effect of post-curing on deformation exhibits significant condition dependency. For laminates manufactured without pressure and complete cure, the post-curing process reduces their deformation. In contrast, laminates subjected to pressure and failing to achieve full cure exhibit increased deformation after post-curing. Excessive pressure during cure even leads to torsional deformation after post-curing treatment.

High-temperature alloys like Incoloy 800HT are widely used in industries such as power generation and chemical processing, where materials must withstand extreme temperatures, mechanical stress, and corrosive environments. This study investigates how microstructural stability and surface product evolution affect the hightemperature performance of Incoloy 800HT alloys. Aging Material A at 875 degrees C enhances mechanical stability and oxidation resistance by promoting TiN and Al2O3 formation along grain boundaries. In contrast, Material B shows increased cracking susceptibility due to less TiN, Al2O3, and M23C6 precipitates. These findings underscore the impact of precipitate distribution on durability under high-temperature stress. In-situ testing further reveals how grain boundary precipitates influence stress distribution and crack behavior, offering insights for designing alloys with improved corrosion resistance and stability in harsh environments.

Carbon fiber reinforced polymer composites (CFRPs) are widely applied in aerospace applications, primarily in the form of laminated structures. Multi-scale CFRPs address manufacturing challenges for complex components by combining continuous fiber layers, which provide the main load-bearing capacity, with discontinuous fiber layers that improve formability and isotropy through co-curing. Currently, a lack of in-depth studies on their failure mechanisms has limited their broader application. This study systematically compares the tensile damage evolution of continuous, discontinuous, and multi-scale CFRPs using an integrated approach that incorporates carbon buckypaper sensors, scanning electron microscopy (SEM), and 3D digital image correlation (3D-DIC). Results show that multi-scale CFRPs exhibit a strength degradation of only about 3.15 % after cyclic loadingunloading, significantly lower than the 9.43 % observed in continuous CFRPs. This structure maintains loadbearing capacity while improving formability. Although multi-scale CFRPs combine both fiber types, their damage mechanisms differ. Combined with fracture toughness verification test, the findings indicate that fiber morphology, length, and continuity play decisive roles in the initiation and propagation of damage. Microscopically, fiber fracture, interface debonding, and matrix cracking exhibit distinct energy dissipation pathways. Macroscopically, discontinuous fibers contribute through "fiber bridging" while continuous fibers enable "stress redistribution", resulting in synergistic energy absorption. These findings establish a damage characterization framework for multi-scale CFRPs structures under tensile loading and significantly advance the development of intelligent composites.

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Microstructure, mechanical properties and corrosion behavior of lightweight (Ti60Cr30Nb10)100−xAlx(x=0, 5, 7.5 and 10,at.%) medium-entropy alloys (MEAs) were investigated in the as-cast and homogenized states. As the Al content increases from 0 to 10 at.%, all the as-cast MEAs consist of identical phase composition, i.e., a body-centered cubic (BCC) phase and a small amount of TiCr2 Laves phase. After the homogenization, all the homogenized MEAs show a single BCC phase. The (Ti60Cr30Nb10)95Al5MEA shows the most excellent mechanical properties both in as-cast and homogenized states among the studied alloys, displaying yield strengths of ∼1048 MPa and ∼1017 MPa along with the compression strain exceeding 50%. Additionally, compared with the TC4 and the as-cast (Ti60Cr30Nb10)95Al5 alloys, the homogenized (Ti60Cr30Nb10)95Al5alloy shows superior corrosion resistance due to its uniform microstructure and chemical composition.

Intricate thermomechanical processing (TMP) including casting, homogenization, cold rolling, annealing and aging, has been widely used to achieve L1 2-strengthened CoCrNi-based medium- and high-entropy alloys (MEAs/ HEAs). However, a large number of parts are usually manufactured by direct casting. We fabricated a nonequiatomic Ni 35 Co 27.5 Cr 27.5 Al 5 Ti 5 HEA consisting of spherical L1 2 nanoprecipitates and FCC matrix using casting, homogenization and aging. Notably, both the homogenized and aged Ni 35 Co 27.5 Cr 27.5 Al 5 Ti 5 HEA samples exhibit equiaxed grains, with the latter showcasing uniformly distributed spherical L1 2 nanoprecipitates in the FCC matrix. The average size and volume fraction of these nanoprecipitates in the aged HEA are-10.9 nm and-41.9 vol%, respectively. Mechanical testing reveals remarkable improvements in the aged HEA, with a yield strength of-916 MPa, an ultimate tensile strength of-1220 MPa, and a total elongation of-21.5 %. The observed enhancement is primarily attributed to precipitation strengthening mechanism. Digital image correlation (DIC) analysis of tensile deformation demonstrates uniform strain distribution in both the homogenized and aged HEA samples. In addition, electron channeling contrast imaging (ECCI) and transmission electron microscopy (TEM) examinations unveil a complex interplay of deformation mechanisms, including multiple planar slip, dislocation shearing coherent L1 2 precipitates, superpartials, stacking fault (SF) networks, and Lomer-Cottrell (L-C) locks. These mechanisms collectively impede dislocation motion, thereby contributing to the excellent strain-hardening ability and outstanding strength-ductility synergy of the HEA.

The dimensional compensation technology can achieve high dense metal parts with precise dimensions for binder jet 3D printing (BJ3DP). In this study, two models (cuboid and gear) of BJ3DP 316L stainless steel (BJ3DP316LSS) parts were established. Numerical simulation and experimental volume shrinkage of the BJ3DP316LSS sintered parts via dimensional compensations technology were investigated. When the dimensional compensation coefficient was set as 1.25, the BJ3DP316LSS cuboids and gears exhibited high densification as 99.6% and 99.4%, respectively. The experimental dimension deviation rates of cuboid and gear parts after dimensional compensations ranged from -3.56% to -0.15% and from 0.89% to 3.42%, respectively. Due to twinning-induced plasticity mechanism, the BJ3DP316LSS sintered gear part via dimensional compensation technology exhibited high hardness (similar to 139 HV), high yield strength (similar to 249 MPa), high ultimate tensile strength (similar to 546 MPa) and excellent elongation (similar to 62%), which are higher than those of the reported 316LSS samples.

In this study, we introduce a novel single-phase Ti 1 & sdot;6 ZrNbMo 0.35 refractory high -entropy alloy (RHEA), synthesized through vacuum arc -melting. The as -cast RHEA demonstrates excellent mechanical properties with a high yield strength of -930 MPa and a large tensile strain of -15.4 %, achieved through severe lattice distortion. Moreover, our investigation reveals the superior corrosion resistance of the RHEA in 3.5 wt% NaCl solution. The remarkable anti -corrosion properties are attributed to the single-phase structure, the increase of Mo 6 + oxides in the passive film and continuous passive oxidation of the elements. This work provides a new and significant approach to designing novel RHEAs with excellent combinations of strength -ductility synergy and superior corrosion resistance.

Microstructure, mechanical properties and corrosion behavior of a Ni34Co28Cr28Al10 multi-principal element alloy (MPEA) were investigated at different states. The as-cast and aged samples exhibited a primary face-cubic centered (FCC) phase and some B2 phase, wherein the FCC phase contained L12 precipitates and the B2 phase contained body-cubic centered (BCC) precipitates. The homogenized sample displayed a single FCC phase. The as-cast sample exhibited the best combination of mechanical properties and corrosion resistance, resulting from multiple strengthening mechanisms, and Al-rich L12 and B2 precipitates which could suppress the transfer of Al atoms to surface leading to increased Cr content in passive film.

Refractory high -entropy alloys (RHEAs) have emerged as promising candidates for high -temperature applications owing to their distinctive mechanical properties. However, their limited tensile ductility and high density pose hurdles for further engineering utilization. In this study, we introduce a novel RHEA composition, Ti 45 Nb 30 Cr 15 V 10 (at.%), distinguished by its reduced density (-6.2 g/cm 3 ), achieved through the assistance of CALPHAD (CALculation of PHAse Diagrams) modeling. The as -cast RHEA exhibits a single body -centered cubic (BCC) structure, demonstrating a tensile yield strength of -904 MPa along with a total elongation of -9.7 %. By employing cold rolling followed by recrystallized annealing (designated as the CRRA sample), we achieve notable enhancements in both strength and ductility. Specifically, the CRRA sample manifests an impressive tensile yield strength of -1010 MPa and a total elongation of -20.6 % at room temperature. Remarkably, even at an elevated temperature of 700 degrees C, the CRRA sample maintains notable strength, displaying a yield strength of -695 MPa. The observed dislocation behavior, transitioning from dual -system slip to multi -system slip, along with the intricate interactions of dislocation substructures (e.g., loops, tangles, networks, bands, and cells) and kink bands, are identified as the principal deformation mechanisms contributing to the exceptional tensile properties of the CRRA sample at room temperature. At 700 degrees C, the presence of wavy -slipping dislocations, induced by the strong pinning effect of component fluctuations, predominantly contributes to the strength of the CRRA sample. However, the emergence of Cr 2 (Ti, Nb, V) Laves phase at grain boundaries results in premature fracture. The extraordinary tensile properties exhibited by the CRRA sample at both room and elevated temperatures underscore its potential for advanced engineering applications.

In this study, the strain hardening behavior and strengthening mechanisms of a mechanically-stable Ti1.6ZrNbAl0.15 lightweight refractory high-entropy alloy (LRHEA) were investigated. The samples were processed by cold-rolling and subsequent annealing to produce fully recrystallized microstructures consisting of a single-phase body-centered cubic (BCC) structure with different mean grain sizes ranging from ∼25 μm to ∼244 μm. The mechanical tests on these samples revealed that grain size refinement had minimal impact on yield strength but effectively improved ductility. Specifically, a low Hall-Petch coefficient of 45 MPa·μm1/2, denoting weak grain boundary strengthening, and a high lattice friction stress of 751 MPa, indicating strong solid solution strengthening, were acquired. These findings underscore the significant role played by lattice distortion in contributing to the strength of this LRHEA. Additionally, in the present LRHEA, dislocation structures demonstrated a planar slip dislocation glide mode. No deformation-induced twinning and phase transformation were observed. As the strain increases, the dynamic slip band spacing refinement serves as the primary mechanism for strain hardening, leading to excellent tensile ductility.

SiCf/SiC ceramic matrix composites are considered highly promising for use in engine thermal structures due to their outstanding properties, including high temperature and corrosion resistance. Nevertheless, the challenging machinability of the material leads to difficulties in material removal, decreased grinding efficiency, and inferior grinding surface quality, prompting the need for further investigation. In this study, a prediction model is developed for the surface roughness of machined composites by integrating the properties of the composites and the maximum undeformed thickness. Furthermore, grinding experiments were performed on 2.5D woven SiCf/SiC composites to validate the model’s reliability and thoroughly investigate grinding characteristics, such as grinding force, temperature, surface roughness, damage morphology, and material removal mechanism. The results demonstrate a low average error rate of 3.7

Intricate thermomechanical processing (TMP) including casting, homogenization, cold rolling, annealing and aging, has been widely used to achieve L12-strengthened CoCrNi-based medium- and high-entropy alloys (MEAs/HEAs). However, a large number of parts are usually manufactured by direct casting. We fabricated a non-equiatomic Ni35Co27.5Cr27.5Al5Ti5 HEA consisting of spherical L12 nanoprecipitates and FCC matrix using casting, homogenization and aging. Notably, both the homogenized and aged Ni35Co27.5Cr27.5Al5Ti5 HEA samples exhibit equiaxed grains, with the latter showcasing uniformly distributed spherical L12 nanoprecipitates in the FCC matrix. The average size and volume fraction of these nanoprecipitates in the aged HEA are ∼10.9 nm and ∼41.9 vol%, respectively. Mechanical testing reveals remarkable improvements in the aged HEA, with a yield strength of ∼916 MPa, an ultimate tensile strength of ∼1220 MPa, and a total elongation of ∼21.5 %. The observed enhancement is primarily attributed to precipitation strengthening mechanism. Digital image correlation (DIC) analysis of tensile deformation demonstrates uniform strain distribution in both the homogenized and aged HEA samples. In addition, electron channeling contrast imaging (ECCI) and transmission electron microscopy (TEM) examinations unveil a complex interplay of deformation mechanisms, including multiple planar slip, dislocation shearing coherent L12 precipitates, superpartials, stacking fault (SF) networks, and Lomer-Cottrell (L-C) locks. These mechanisms collectively impede dislocation motion, thereby contributing to the excellent strain-hardening ability and outstanding strength-ductility synergy of the HEA.

The study of alloys exhibiting noteworthy strength-ductility synergy at ambient and cryogenic temperatures has been a persistent area of interest in materials engineering. This interest extends to the recent development of high-entropy alloys (HEAs). The current investigation delves into the impact of diverse thermo-mechanical treatments on the phase and microstructure evolution in a face-centered cubic (FCC) Al7.5Co20.5Fe24Ni24Cr24 HEA. The transition from solid-solution annealing to recrystallization annealing leads to the formation of the desired hierarchical B2+L12+σ precipitates, accompanied by a heterogeneous FCC matrix. The initiation of the B2 phase originates from nucleation on defect-rich sites, such as deformation bands. However, the coherent L12 phase homogeneously forms in the FCC matrix at intermediate temperature aging, as these sites are scarce or occupied. A heterogeneous structure emerges from the transition in annealing temperatures and the pinning effect of the B2 precipitates. The resulting heterogeneous structure exhibits an exceptional strength-ductility synergy at both room and liquid nitrogen (LN2) temperatures. This is evident in its mechanical properties with a yield strength of ∼717 MPa / ∼1109 MPa, an ultimate tensile strength of ∼1086 MPa / ∼1609 MPa, and an elongation of ∼34.3% / ∼43.2% at room / LN2 temperatures. The formation of deformation twins (DTs) is facilitated by localized stress buildup from hetero-deformation-induced (HDI) hardening stress at room temperature. The exceptional strength and ductility at LN2 temperature are attributed to a combination of factors. These include a high-density of stacking faults (SFs), DTs, and their interactions, including those with precipitates, SFs-based substructures, and Lomer-Cottrell locks. These multiple deformation mechanisms ensure consistent and sustained strain-hardening even under substantial strain. This paper sheds light on the complex interplay of microstructure, deformation mechanisms, and mechanical properties in the Al7.5Co20.5Fe24Ni24Cr24 HEA, potentially guiding the development of ultra-strong yet ductile alloys for cryogenic applications.

As-cast alloys generally require additional processing steps before optimal strength-ductility combinations can be achieved, thereby impeding the progress of manufacturing high-performance metallic products by direct casting. Here we report a novel low-cost FeNi0.9Cr0.5Al0.4 high entropy alloy with unique fibrous heterogeneous solidification microstructure, i.e., fibers-like face-centered-cubic soft phases that are enveloped in nano-sized ordered body-centered-cubic hard shells. This fibrous microstructure is thought to be responsible for the notable mechanical properties, which includes a yield strength of ∼670 MPa and an ultimate tensile strength of ∼1196 MPa, together with a uniform elongation of ∼21.1% at room temperature. Experimental results confirm the suggestion that the combination of a high strength and good ductility can be attributed to the hetero-deformation induced hardening mechanism generated from the soft-fiber and hard-shell interface. The cost-effectiveness of this as-cast FeNi0.9Cr0.5Al0.4 alloy with its unique fibrous structure and outstanding tensile properties renders it an ideal candidate for structural applications.

To demonstrate the concept of lightweight refractory high-entropy alloys (LRHEAs) with remarkable strength and ductility at room- and high-temperatures, we designed and fabricated novel Ti1.6ZrNbAlx (x = 0.3, 0.4, 0.5 and 0.65) LRHEAs with a relatively low density (<∼5.9 g/cm3). The presence of B2 coherent precipitates and their interactions with moving dislocations is proposed to be responsible for the measured high tensile yield strength (>800 MPa) and satisfactory tensile ductility (>10%) at room-temperature. The compressive peak stress exceeding 500 MPa at 600 °C supports the potential application of these LRHEAs as high-temperature structural materials. Our work provides a framework that can be used to guide the design of high-performance LRHEAs for high-temperature applications.

The development of alloys with good combinations of strength-ductility and corrosion resistance is a long-standing research theme for advanced materials engineering, which also holds true for the newly emerged high-entropy alloys (HEAs). Here, Ni/Ti-rich precipitates and heterogeneous structure were introduced for the primary purpose of improving strength-plasticity synergy of a Co-free Fe4Ni4Mn2CrTi HEA with good anti-corrosion performance. Specifically, four typical states of this HEA were tailored and compared, including i) as-cast, ii) homogenized, iii) post deformation annealing (PDA) sample with heterogeneous structure and iv) PDA sample with homogeneous structure. The structural features, mechanical properties, and underlying phase transformation mechanisms were systematically investigated. Phase transformation of η-D024 to γ′-L12 was realized during annealing treatments, based on the intrinsic stacking faults formed by repeating removal of the (0001) planes in the η structure. Compared with the homogenized counterpart, the strength-ductility synergy was achieved in the alloy iv, showing an evident increment of ∼43.4% in yield strength (σ0.2) and ∼57.8% in ultimate tensile strength (σUTS), respectively, resulting from solid-solution strengthening, grain-boundary strengthening and precipitation strengthening, yet without sacrificing ductility. Good combinations of strength and ductility were also achieved in the alloy iii with heterogeneous structure, possessing an even higher σ0.2 and σUTS yet maintaining a moderate elongation, whose strength contribution from hetero-deformation induced hardening is recognized as a significant strengthening mechanism. Additionally, in comparison with the conventional corrosion-resistant 304 stainless steel, compact TiO2 and Cr2O3 in the passive film give rise to more superior anti-corrosion properties of the homogenized HEA. This paper provides a new paradigm in the controllable design of novel low-cost high-performance HEAs for achieving their potential structural and functional engineering applications.

Ti40Nb25Cr15Mo10Al10 and Ti40Nb20Cr20Mo10Al10 refractory high-entropy alloys (RHEAs) were designed and fabricated, aiming at investigating their mechanical properties, corrosion and tribo-corrosion behavior in molten aluminum. Compared with H13 steel, these RHEAs exhibit significantly better combinations of high-temperature mechanical properties, corrosion and tribo-corrosion resistance. Low solubility of constituent elements in molten aluminum along with slow diffusion of Al atoms in RHEAs' matrices, are responsible for the outstanding corrosion resistance of RHEAs. Exceptional tribo-corrosion resistance of RHEAs derives from their outstanding combinations of corrosion resistance and high-temperature mechanical properties. Additionally, higher content of Cr in RHEAs would lead to worse tribo-corrosion resistance.