As-cast Al0 Research Articles

Influence of hot forging on grain formation in Al0.35CoCrFeNi high-entropy alloy: numerical simulation, microstructure and mechanical properties

One-step (F100) and three-step (F30-60-40) hot forging of Al0.35CoCrFeNi alloy was investigated to achieve a uniform equiaxed grain structure. In the as-cast and forged state, only a single-phase face-centered cubic structure was observed. The formation of twins, recrystallized and partially recrystallized grains in the volume of the samples was observed depending on used forging process. To predict uniform grain-size formation numerical simulation of the hot-forging process was used. The numerical model was calibrated and validated by means of measured compression experimental data of as-cast Al0.35CoCrFeNi alloy before forging. Thermal analysis using finite element analysis was used to simulate cooling of sample during the relocation from the furnace on the lower die. Simulations were run under different thermo-mechanical conditions and the regions for the formation of dynamically recrystallized grains were predicted. Room temperature mechanical properties were evaluated after F100 and F30-60-40 hot-forging process. The F30-60-40 hot forging optimized the grain size, which was evident in the very small dispersion of the room temperature mechanical properties in tension. Elongation after F30-60-40 hot forging increased by 17%. The correlation between temperature, equivalent stress, equivalent plastic strain, microstructure, tensile properties, and strain-hardening behavior is discussed.

Ultra-High Strength in FCC+BCC High-Entropy Alloy via Different Gradual Morphology.

In this study, high-pressure torsion (HPT) processing is applied to the as-cast Al0.5CoCrFeNi high-entropy alloy (HEA) for 1, 3, and 5 turns. Microstructural observations reveal a significant refinement of the second phase after HPT processing. This refinement effect is influenced by the number of processing turns and the distance of the processing position from the center. As the number of processing turns or the distance of the processing position from the center increases, the fragmentation effect on the second phase becomes more pronounced. The hardness of the alloy is greatly enhanced after HPT processing, but there is an upper limit to this enhancement. After increasing the number of processing turns to 5, the increase in hardness at the edge becomes less significant, while the overall hardness becomes more uniform. Additionally, the strength of the processed alloy is significantly enhanced, while its ductility undergoes a noticeable decrease. With an increase in the number of processing turns, the second phase is further refined, resulting in improvement of strength and ductility.

Tailored precipitation assisted by laser-induced cellular dislocation network structures in Al0.3CoCrFeNi high entropy alloy

Cellular dislocation network structures play a critical role in strengthening metals, while their ability to tailor the precipitation of second-phase particles has long been overlooked. Herein, a novel strategy combining laser surface treatment and two-steps annealing is proposed to produce B2 network structures in the as-cast Al0.3CoCrFeNi high-entropy alloy. Cellular dislocation network structures are first introduced in the plates by the laser surface treatment on both sides, then the L12 phase is precipitated on the wall of the dislocation networks by annealing at 700 °C. During second annealing at 800 °C, previously precipitated L12 precursors provide kinetically preferred sites and element segregation for the precipitation of the B2 phase, finally forming dense B2 network structures within the defect-scarce matrix. Dislocations can easily move inside the network structures, and they are blocked by the B2 particles in the wall areas, thus presenting a superior strength-ductility synergy.

The Effects of the Al and Zr Contents on the Microstructure Evolution of Light-Weight AlxNbTiVZry High Entropy Alloy.

To investigate the comprehensive effects of the Al and Zr element contents on the microstructure evolution of the AlNbTiVZr series light-weight refractory high entropy alloys (HEAs), five samples were studied. Samples with different compositions were designated Al1.5NbTiVZr, Al1.5NbTiVZr0.5, AlNbTiVZr, AlNbTiVZr0.5, and Al0.5NbTiVZr0.5. The results demonstrated that the actual density of the studied HEA samples ranged from 5.291 to 5.826 g·cm-3. The microstructure of these HEAs contains a solid solution phase with a BCC structure and a Laves phase. The Laves phase was further identified as the ZrAlV intermetallic compound by TEM observations. The microstructure of the AlNbTiVZr series HEAs was affected by both the Al and Zr element contents, whereas the Zr element showed a more dominant effect due to Zr atoms occupying the core position of the ZrAlV Laves phase (C14 structure). Therefore, the as-cast Al0.5NbTiVZr0.5 sample exhibits the best room temperature compression property with a compression strength (σp) of 1783 MPa and an engineering strain of 28.8% due to having the lowest ZrAlV intermetallic compound area fraction (0.7%), as characterized by the EBSD technique.

Effect of Heat Treatment on the Microstructure and Mechanical Properties of the Al0.6CoCrFeNi High-Entropy Alloy.

The effect of heat treatment on the microstructure and tensile properties of an as-cast Al0.6CoCrFeNi high-entropy alloy (HEA) was investigated in this paper. The results show that the as-cast Al0.6CoCrFeNi HEA presents a typical FCC dendrite morphology with the interdendritic region consisting of BCC/B2 structure and heat treatment can strongly affect the microstructure and mechanical properties of HEA. Microstructure analysis revealed the precipitation of a nano-sized L12 phase in the FCC dendrite and the formation of the FCC and σ phases in the interdendritic region after annealing at 700 °C. The coarse B2 phase was directly precipitated from the FCC dendrite in the 900 °C-annealed sample, with the coexistence of the B2, FCC, and σ phases in the interdendritic region. Then, the interdendritic region converted to a B2 and FCC dual-phase structure caused by the re-decomposition of the σ phase after annealing at 1100 °C. The tensile test results show that the 700 °C-annealed HEA presents the most significant strengthening effect, with increments of corresponding yield strength being about 107%, which can be attributed to the numerous nano-sized L12 precipitates in the FCC dendrite. The mechanical properties of 1100 °C-annealed alloy revert to a level close to that of the as-cast alloy, which can be attributed to the coarsening mechanism of B2 precipitates and the formation of a soft FCC phase in the interdendritic region. The observed variation in mechanical properties during heat treatment follows the traditional trade-off relationship between strength and plasticity.

High temperature deformation behaviour of as-cast Al0.4Co0.9Cr1.2Fe0.9Ni1.2(Si, Ti, C, B)0.375 complex concentrated alloy during tensile and compression tests

High temperature deformation behaviour of as-cast Al0.4Co0.9Cr1.2Fe0.9Ni1.2(Si, Ti, C, B)0.375 complex concentrated alloy during tensile and compression tests

Effect of Pt Addition on the Oxidation and Corrosion Resistance of Al0.25CoCrFeNi High-Entropy Alloy

The effect of minor platinum alloying on the microstructure, phase composition, oxidation and corrosion resistance of Al0.25CoCrFeNi high-entropy alloy (HEA) has been studied. It was observed that Pt does not segregate as a separate phase, but it is incorporated into the fcc solid solution. High-temperature oxidation of the as-cast Al0.25CoCrFeNi and Al0.25CoCrFeNiPt0.1 high-entropy alloys was carried out in a muffle furnace under isothermal conditions at 900 °C for 0–50 h (weighing was carried out every 10 h) in air atmosphere. The specific weight gain decreased from 0.58 mg/cm2 for Al0.25CoCrFeNi to 0.31 mg/cm2 for the platinum-doped Al0.25CoCrFeNiPt0.1 sample. It was determined that Pt triggers the formation of an interlayer Al-rich oxide phase between the outer Cr-rich oxide layer and the interior of the alloy, significantly reducing the oxidation rate of Al0.25CoCrFeNiPt0.1 HEA. Electrochemical tests in 0.5 M H2SO4 solution demonstrated passive behavior with anodic control of the process.

Investigation of mechanical behavior, constitutive modeling, and fracture criteria for as-cast Al0.3CoCrFeNi high entropy alloy

High entropy alloys (HEAs) have garnered significant attention in recent years, primarily focusing on alloying design and thermal processing. The objective of this study was to investigate the mechanical response of Al0.3CoCrFeNi, a representative HEA, under various stress states, temperatures, and strain rates, aiming to establish its constitutive equation and fracture criteria. Employing a hybrid FEM/EX approach, the constitutive behaviour of the alloy was characterized using the modified Johnson-Cook (MJC) model, while the fracture properties were assessed using the Hosford-Coulomb (HC) equation. Experimental findings highlighted the remarkable tensile strength (578.1 MPa) and ductility (69%) of the as-cast Al0.3CoCrFeNi at room temperature. However, at elevated temperatures ranging from 400 °C to 650 °C, a reduction in ductility was observed, accompanied by serration behaviour. Notably, precipitation hardening was detected at 800 °C, indicative of strengthening through precipitate formation. Additionally, Al0.3CoCrFeNi exhibited significant strain rate sensitivity and a positive strain rate effect, emphasizing its dynamic response under different loading conditions. The accuracy of the constitutive model and fracture criteria was validated through the examination of deformation and fracture modes in Taylor impact tests. The MJC model demonstrated predictions within a 10% deviation from experimental data, while the HC fracture criterion, accounting for stress triaxiality and Lode parameters, effectively predicted shear fracture in the projectiles. Crack formation in the projectiles resulted from a combination of tension and shear, followed by propagation at a 45° angle under combined compression and shear loading. This comprehensive study enhances understanding of the mechanical properties of Al0.3CoCrFeNi, providing valuable insights for its application in engineering, particularly in impact protection.

Corrosion Resistance of Al0.5CoCrFeNiCuxAgy (x = 0.25, 0.5; y = 0, 0.1) High-Entropy Alloys in 0.5M H2SO4 Solution.

The electrochemical behavior of the as-cast Al0.5CoCrFeNiCuxAgy (x = 0.25, 0.5; y = 0, 0.1) high-entropy alloys (HEAs) in a 0.5M H2SO4 solution was studied. Polarization measurements were carried out in a standard three-electrode electrochemical cell at room temperature using a platinum counter electrode and a saturated silver chloride reference electrode. For Al0.5CoCrFeNiCu0.5 and Al0.5CoCrFeNiCu0.5Ag0.1, copper segregation along the grain boundaries was observed, which highly dissolved in the sulfuric acid solution and resulted in low corrosion resistance of the samples. Introducing Ag into Al0.5CoCrFeNiCu0.25 HEA led to the precipitation of a copper-silver eutectic structure, in which the copper regions were selectively dissolved in the sulfuric acid solution. Al0.5CoCrFeNiCu0.25 exhibited the best corrosion resistance with the corrosion current density of Icorr = 3.52 ± 0.02 μA/cm2, significantly superior to that of the Al0.5CoCrFeNi sample without copper and silver (Icorr = 6.05 ± 0.05 μA/cm2). Finally, the results indicated that suppressing elemental segregation by annealing or tailoring chemical composition is essential to improve the corrosion resistance of Al0.5CoCrFeNiCuxAgy HEAs.

Carbon-driven coherent nanoprecipitates enable ultrahigh yield strength in a high-entropy alloy

A novel C-doped high entropy alloy (Al0·5CoFeNiC0.1) with nano-scale coherent precipitates was successfully designed and fabricated by arc-melting. The nano-scale phase has been studied using a complementary range of techniques such as X-ray diffraction (XRD), transmission electron microscopy (TEM), atom probe tomography (APT) and density functional theory (DFT). The effect of nano-sized particles on the mechanical behavior of the alloy has been evaluated by tensile testing. The nano-sized precipitate was identified to be the off-stoichiometric κʹ phase, which has an L′12-crystal structure, wherein Fe/Ni/Co and Al are ordered on simple cubic sublattices and C occupies the octahedral interstices surrounded by only transition metal atoms, together forming a perovskite-type structure. DFT simulation shows that C triggers the ordered arrangement of Al and Fe/Ni/Co, thus promoting the formation of κʹ phase. κʹ particles precipitate during cooling after solidification via a classical nucleation and growth mechanism. An addition of only 2.8 at.% C to as-cast Al0·5CoFeNi leads to a high volume fraction (∼55%) of κ′ precipitates with an average size of ∼35 nm in as-cast Al0·5CoFeNiC0.1, thus enhancing dramatically the yield strength by a factor of 3 (from 385 MPa to 1115 MPa) compared to its carbon free counterpart (Al0·5CoFeNi). Such an efficient strengthening effect on κʹ phase could be associated with its high antiphase boundary (APB) energy.

Effect of Mn on microstructure and tensile properties of as-cast Al0.5CoFeNiC0.1 high-entropy alloy

The effect of Mn on the microstructure and tensile properties of Al0.5CoFeNiC0.1 HEA (high-entropy alloy) has been investigated using electron microscopy, atom probe and mechanical testing. The results show that addition of Mn refines dendrite and grain and reduces volume fraction of B2 phase and interdendritic regions. Mn is demonstrated to be not the former of κ′ phase. Therefore, the addition of Mn reduces the size and volume fraction of the κ′ phase, leading to a reduction in the yield strength of the HEA whereas an enhancement in ductility. 7.7 at.% Mn doping makes the HEA (Mn0.3) have a good balance between yield strength (1 GPa) and ductility (23% elongation). Adding Mn does not change deformation mechanism of the HEAs.

High temperature tribological performance of a cost-effective eutectic high entropy alloy Al0.8CrFeNi2.2: Comparison with AlCoCrFeNi2.1

A comprehensive comparison study on microstructure, mechanical and high temperature tribological performance of as-cast Al0.8CrFeNi2.2 and AlCoCrFeNi2.1 eutectic high entropy alloys was conducted. The cost-effective Al0.8CrFeNi2.2 exhibited higher hardness and tensile strength than AlCoCrFeNi2.1. AlCoCrFeNi2.1 showed better friction and wear performances than Al0.8CrFeNi2.2 at RT, but an opposite trend was observed when temperature exceeded 300 oC. Higher Ni content in FCC and BCC(B2) phases of Al0.8CrFeNi2.2 are found to increase the hardness of constitution phases. The tribolayers of Al0.8CrFeNi2.2 at 900 oC composes of distinguished oxide layer and ultrafine-grained particles layer, which are different from the mixing pattern in AlCoCrFeNi2.1. A relatively thicker tribo-layer is also found to enhance the high temperature tribological properties of Al0.8CrFeNi2.2.

As-cast Co-free Al0.4Ni0.4CrFe high entropy alloy with hierarchical coherent precipitates and remarkable mechanical properties

In this paper, a novel Co-free low-cost Al0.4Ni0.4CrFe high entropy alloy (HEA) with hierarchical coherent precipitates was designed and fabricated by arc-melting. The as-cast Al0.4Ni0.4CrFe HEA is composed of Fe-Cr-enriched disordered body-centered cubic (BCC) matrix and even-distributed hierarchical coherent ordered BCC (B2) precipitates, i.e., primary submicron precipitates (∼194 nm) and secondary nanoprecipitates (∼14 nm). The as-cast Al0.4Ni0.4CrFe HEA shows outstanding compressive properties, i.e., a compressive yield strength of ∼1513 MPa and a compressive strength of ∼3085 MPa, which are superior to most previously reported CoNiCrFe-based HEAs containing costly Co elements. The extraordinary mechanical properties are ascribed to the hierarchical coherent precipitates-induced strengthening. These results showed that introducing hierarchical precipitates into Co-free HEAs through compositional design is an effective strategy to achieve superior combinations of high strength and low-cost, which is beneficial for the practical engineering applications of HEAs.

Synergistic effect of Ti, B, Si, and C on microstructure and mechanical properties of as-cast Al0.4Co0.9Cr1.2Fe0.9Ni1.2(Si, Ti, C, B)0.375 complex concentrated alloy

The synergistic effect of Ti, B, Si, and C on microstructure and mechanical properties of as-cast Al0.4Co0.9Cr1.2Fe0.9Ni1.2(Si, Ti, C, B)0.375 complex concentrated alloy (CCA) was studied. The as-cast alloy was prepared by vacuum induction melting in a ceramic crucible followed by a tilt casting to a graphite mould. The effect of alloying elements on the primary solidification phase, solidification path, and phase transformation temperatures is evaluated. The solidification of the alloy starts with the growth of columnar FCC(A1) (face-centred cubic crystal structure A1) dendrites and is finalised by the formation of lamellar FCC(A1) + (Ni,Co,Fe)16(Ti,Cr)6(Si,Al)7 eutectic in the interdendritic region. During solidification, Al, Ti, B, Si, and C segregate preferentially to liquid, which leads to the formation of BCC(B2) (ordered body-centred cubic crystal structure B2), BCC(A2) (body-centred cubic crystal structure A2), FCC(A1), (Ni,Co,Fe)16(Ti,Cr)6(Si,Al)7, Cr2B, and TiC phases in the interdendritic region. The highly anisotropic microstructure of tensile specimens prepared from the as-cast alloy consists of columnar FCC(A1) dendrites (89 vol%) oriented at an angle ranging from 75 to 90 degrees to the longitudinal axis of specimens and multiphase interdendritic region (11 vol%). The tensile deformation curves show only the strain hardening stage at test temperatures up to 700 °C. The strain hardening coefficient decreases from 0.20 to 0.17 by increasing the test temperature from 20° to 700°C. At temperatures ranging from 725° to 900°C, the tensile curves show the strain hardening stage, which is followed by the strain-softening stage up to a fracture. The strain softening stage results from dynamic recrystallisation of FCC(A1) dendrites and fracture of brittle high elastic modulus phases in the interdendritic region.

Corrosion behaviors related to the microstructural evolutions of as-cast Al0.3CoCrFeNi high entropy alloy with addition of Si and Ti elements

In this work, the electrochemical potentiodynamic polarization and impedance spectroscopy analysis were used to investigate the corrosion behaviors related to microstructural evolutions of Al0.3CoCrFeNiSix and Al0.3CoCrFeNiTix HEAs in the NaCl solution. The results presented that addition of Si promoted the formation of BCC phase, which was regarded as a micro-anode to prevent FCC phase as a micro-cathode from being corroded. While the volume fraction of BCC phase increased to enhance the corrosion resistance of Six alloys with increasing Si content. Furthermore, the reduction in the grain sizes of Six alloys with increasing Si content could also improve corrosion resistance of the alloys. Therefore, the corrosion resistance of Six alloys was increased with increasing Si content. Addition of Ti with a high corrosion resistance of Clˉ caused the reduction in the grain sizes of Tix alloys, which can improve the corrosion resistance of alloys. However, the high Ti content can destroy the corrosion resistance of the alloys due to the formation of a large amount of precipitated phases. Therefore, as Ti with atomic percentage be equal to that of Al can effectively eliminate the negative influence of precipitated phases and microstructure on the corrosion resistance of alloys, meaning the Ti0.3 alloy had the best corrosion resistance in Tix alloys. The analysis of X-ray photo-electron spectroscopy (XPS) identified that the contents of oxidized Cr3+ and Fe3+ in the passive film are the main contribution to improve the corrosion resistance of Six alloy. And the contents of oxidized Cr3+ and Ti4+ in the passive film are the main contribution to improve the corrosion resistance of Tix alloy.

Evolution of the microstructure and mechanical properties of as-cast Al0.3CoCrFeNi high entropy alloys by adding Si content

In this paper, a set of as-cast Al0.3CoCrFeNiSix (values of x is 0, 0.1, 0.2, 0.3, 0.4, 0.5) HEAs were fabricated by arc vacuum melting. The evolutions of microstructure and mechanical properties of alloys were systematically investigated. The results revealed that addition of Si could promote formation of (Al, Ni, Si)-rich phase with B2 structure (BCC1 phase) and (Fe, Cr)3Si phase with L21 structure (BCC2 phase). The microstructure of alloys changed from a single FCC phase to mixed FCC plus BCC1/BCC2 phases with a typical dendritic structure with increasing Si content. Meanwhile, addition of Si could improve the hardness and strength of alloys, the hardness and yield strength of alloys increased from 141 ± 2.0 to 445 ± 6.6 HV and 167 ± 4.3 to 713 ± 5.7 MPa with increasing Si content. According to the relationship between microstructure and mechanical properties, the strengthening mechanisms of current HEAs were evaluated, demonstrating that precipitation strengthening of ordered BCC phase is the dominant strength mechanism.

Evolution of phase, microstructure and mechanical properties of as-cast Al0.3CoCrFeNiTix high entropy alloys

Al0.3CoCrFeNi high entropy alloy (HEA), as a widely studied alloy with excellent plasticity and low strength has received a widespread attention. In this work, the strength of this alloy could be improved by addition of Ti for satisfying its engineering application. And then the effect of Ti on the evolutions of phase, microstructure and corresponding mechanical properties of as-cast Al0.3CoCrFeNiTix HEAs were investigated. The results demonstrated that addition of Ti could promote the microstructure of the alloys transforming from a single-phase structure to a typical dendritic structure. Simultaneously, minor Ti content caused formation of the (Al, Ni, Ti)-rich L12 phase in alloys, and then further addition of Ti content promoted formation of the (Co, Ti)-rich Laves, (Ni, Ti)-rich γ and (Fe, Cr)-rich σ phases in the Ti0.3, Ti0.4 and Ti0.5 alloys. The volume fraction of these phases increased with Ti content increasing. The evolutions of the phase and microstructure greatly modified the mechanical properties of the alloys. With the increase of Ti content, the hardness of the alloys increases from 124 (Ti0) to 448 (Ti0.5) HV, and the yield strength from 167 (Ti0) to 698 (Ti0.4) MPa. Based on the correlation between microstructure and strength, the strengthening mechanisms of current HEAs were analyzed, confirming that the precipitation strengthening is the dominant strengthening mechanism.

Thermal physical properties of high entropy alloy Al0.3CoCrFeNi at elevated temperatures

In high entropy alloys (HEAs), the nanoscale precipitations and short-range orders affected the material's mechanical properties and brought about changes in the thermal physical properties. As-cast Al0.3CoCrFeNi was prepared, and an ideal random disorder HEA model was established by molecular dynamics (MD). The resistivity, thermal conductivity, specific heat capacity and linear expansion coefficient at 300–1100 K were obtained and discussed by experiments and simulations. The intracrystalline segregation was observed in the as-cast HEA. At about 600–800 K, the resistivity growth stagnated, and two exothermic and one downward heat capacity peaks were found in DSC and specific heat, respectively. The metastable structure of as-cast HEA was ordered and a small amount of nano-phase precipitated. When above 800 K, the resistivity increased rapidly, DSC and specific heat appeared endothermic peak and extensive range upward heat capacity peak respectively. The alloy underwent an order-disorder transition accompanied by a small amount of phase decomposition. Phonons were the main force of heat conduction. Thermal conductivity and lattice thermal conductivity show the weak temperature dependence of T−0.66 and T−0.48, respectively. The experimental results, affected by intragranular segregation and ordering, differed from the simulation results at lower temperatures while agreed well with the simulation results at higher temperatures. The order degree on thermodynamic parameters of as-cast HEA during the heating process should be considered in subsequent studies.

Excellent tensile property and its mechanism in Al0.3CoCrFeNi high-entropy alloy via thermo-mechanical treatment

Al0.3CoCrFeNi is one of the widely studied high-entropy alloys (HEAs) due to the superior properties; however, its strength at room temperature is not satisfactory. The thermo-mechanical method was usually used to tune the mechanical property of materials. Here the as-cast Al0.3CoCrFeNi HEA was cold rolled and subsequently annealed for various times. The microstructural variation was characterized by X-ray diffraction, electron backscatter diffraction and transmission electron microscopy and the mechanical properties were estimated by microhardness and tension tests. It was found that the shorter annealing time led to a finer grain size and higher hardness. Besides, the yield strength of ~467 MPa, ultimate tensile strength of ~830 MPa and tensile elongation of ~48% were achieved in the thermo-mechanically processed alloy, which was comparable with or even a little higher than the previously reported data. The excellent combination of strength and ductility in this alloy was mainly ascribed to the combined action of residual dislocations, refined grains, and annealing and deformation twins in the dislocation motion. The calculated results of the contributions from different strengthening mechanisms to yield strength were well consistent with the experimental data.

Influence of Mo/Cr ratio on the lamellar microstructure and mechanical properties of as-cast Al0.75CoCrFeNi compositionally complex alloys

The Al0.75CoCrFeNi alloy (Al16Co21Cr21Fe21Ni21 in at.%) presents a lamellar microstructure in the as-cast state consisting of a spinodally-decomposed B2/BCC matrix and Widmanstätten-type FCC plates. In this study, to retain the lamellar microstructure and improve tensile strength, Al16Co21Cr21-xFe21Ni21Mox alloys with x ≤ 10 at.% were investigated. For x = 2 at.%, the Widmanstätten microstructure changed into a vermicular one due to the stabilization of the BCC phase. With increasing the Mo/Cr ratio, the BCC phase transformed into topologically close-packed (TCP) phases, i.e., σ phase for x = 4 at.% and R phase for x ≥ 6 at.%, whose volume fractions increases with x. The as-cast alloys with x = 10 and 4 at.% presented the largest microhardness of ~600 HV0.5. The former had the highest volume fraction in TCP phases, which are hard and brittle while the latter presented the finest microstructure (enhanced phase boundary strengthening). While the alloys with x > 4 at.% were too brittle to machine tensile specimens, the others were tested between 20 and 700 °C. The ultimate tensile strength increased with increasing x up to ~1460 MPa for x = 4 at.% at 400 °C. At 700 °C, the strength of all alloys significantly decreased due to the softening of the B2 phase. Most of them had limited ductility and showed intergranular fracture except for x = 4 at.% presenting pronounced necking with ~38% ductility. The latter effect was attributed to the occurrence of interfacial sliding resulting in cavitation at grain boundaries and interphase boundaries.