Recently, High entropy alloys (HEAs) advanced into high-temperature applications as potential candidates by enduring high temperatures with high thermal stability, higher oxidation and corrosion resistances, thermal fatigue, and creep resistances. HEAs acquire unique characteristics called core effects of HEAs: high entropy effect, sluggish diffusion effect, severe lattice distortion, and cocktail effect. HEAs frequently exhibit remarkable properties because of having such unique core effects. Thus, the emergence of HEAs has gained significant interest in the field of materials leading to a contemporary point of discussion on their exciting nature and properties. The current review article intends to summarize the significant works on the oxidation behavior of High entropy alloys (HEAs). Also, peculiar attention has been invested in comprehending oxidation behavior of HEAs in the viewpoint of the crystal structure that is BCC-HEAs, FCC-HEAs and few case studies were compared with the conventional alloys. Current challenges and essential future directions in this field are also pointed out.

No abstract

Mechanical properties relating to the thermally activated process of yielding was investigated in Ti6Al4V with a bimodal microstructure, consisting of both primary alpha grains and lamellar colonies of secondary alpha/beta lamellae. The temperature dependence of yield stress, effective stress, activation volume, and activation enthalpy were investigated between 77 K and 650 K. The yield stress and effective stress decreased with increasing temperature. It was found that the temperature dependence of activation enthalpy for yielding shows values between those obtained from basal slips and prismatic slips investigated in single crystalline ¡-titanium. This suggests that the thermally activated processes which control the yielding of bimodal Ti6Al4V is the combination of basal and prismatic slips.

The harsh operating conditions of the oxygen evolution reaction (OER) in water electrolysis severely degrade the activity and stability of the electrocatalysts due to elemental leaching or particle agglomeration. Therefore, it is crucial to incorporate support materials that effectively immobilize catalyst particles for developing efficient OER catalysts. This review aims to highlight the role of MXene as a support material to improve the performance of OER catalysts. First, the extended OER mechanism is briefly described in terms of the effect of MXene support on OER catalysts. Then, various synthesis methods of MXene and catalyst‐MXene compounds are introduced, and important properties of MXene that are beneficial to improve OER performances are discussed. The electrocatalytic results of the enhanced OER catalysts due to the effective MXene support are also summarized. Finally, future challenges and prospects are proposed for utilizing MXene as an excellent support material for various electrocatalysis.

The temperature dependence of the fatigue crack propagation rate in stage IIb in bimodal Ti6Al4V was investigated at different stress ratios R. Fatigue tests were conducted between room temperature and 550 K at R of 0.1, 0.7, 0.8, and 0.9, and two phenomena were elucidated consequently. First, the fatigue crack growth rates were nearly temperature independent for R = 0.1, 0.7, and 0.8 while it is temperature dependent at R = 0.9. This difference in the temperature dependence can be explained by the assumptions that the fatigue crack growth is controlled by the dislocation activities associated with work-hardening for R¯0.8 while it is controlled by dislocation glide at R = 0.9. Second, the fatigue crack growth rates at R = 0.9 was higher than those at R = 0.1, 0.7, and 0.8. This increase in the fatigue crack growth rate at R = 0.9 can be explained by the change in the stress intensity factor of crack opening. Both the controlling mechanisms emanated from the change in the dislocation structure in front of the crack tip.