The effect of Cu and Mn elements on the mechanical properties of single-crystal CoCrFeNi-based high-entropy alloy under nanoindentation

Abstract

Considering the impact of chemical compositions, the mechanical properties and microstructure evolution of the single-crystal FCC CoCrFeNi-based high-entropy alloys (HEAs) are investigated by using molecular dynamics simulation in nanoindentation. The addition of Cu and Mn elements would decrease the stacking faults energy resulting in the dislocation-mediated deformation. Moreover, the total number of chemical compositions of CoCrFeNi-based HEAs has critical effects on the results according to the Hertz contact theory. The plastic deformation is studied by correlating the P–h curve with the instantaneous defect structure and dominated by nucleation of Shockley partial dislocations or the motions of stacking faults. Owing to the large amount of Hirth and Stair-rod dislocations, CoCrFeNiCu HEA has the largest indentation force, next followed by CoCrFeNi and CoCrFeNiMn HEAs. Then, the influence of chemical composition on the radial distribution function is explored, and it exhibits that Cu and Mn elements are conducive to amorphization. Finally, the analysis of microstructure evolution reveals that the Mn addition would contribute to the slipping process for CoCrFeNi-based HEAs causing the decrease of indentation force and hardness. In contrast, the Cu addition results in irregular slipping mode accompanying the appearance of dislocation loops. In this simulation, the mechanical properties of single-crystal CoCrFeNi-based HEAs are strongly dependent on the chemical composition, which contributes to the composition design of high entropy alloys in the future.

Atomistic evaluation of tension–compression asymmetry in nanoscale body-centered-cubic AlCrFeCoNi high-entropy alloy

“…In recent years, MD simulations were widely utilized to study the mechanical properties and deformation mechanisms of the HEAs. The predicted results from these MD simulations [26][27][28][29][30][31][32] can not only agree well with the experimental data but also reveal the new deformation mechanisms at microscale that is difficult to obtain in experiments.…”

Effect of copper on microstructural evolution and mechanical properties of laser-welded CoCrFeNi high entropy alloy

“…The dimple size difference is due to the extent of inclusion present for microvoid initiation. A smaller size indicates greater inclusion (Cr-rich oxide) due to laser welding [16]. Coarse dimples are observed in CoCrCuFeNi BM in Figure 10(c), while welded CoCrCuFeNi shows tear edge and cleavage step, which is characteristic of quasi-cleavage fracture.…”

“…LW of CoCrFeNi alloy has been reported by Zhu et al [13]. It has been reported that the addition of Cu to CoCrFeNi alloy improves the high-temperature wear, hardness and irradiation stability [14-16]. To the best of our knowledge, the effect of Cu on the weldability of CoCrFeNi has not been studied yet.…”

Effect of Mn-content of ER5356 welding rods on mechanical properties of Al-alloys joints

“…In the first phase of the ER5356-WWS preparation study, the first task was to understand the compositional design of the ER5356-AA and the effects of its extrusion and drawing process (Qi et al, 2021;Naing and Muangjunburee, 2022). This phase of the study provided the basis for subsequent welding bar preparation and WWS analysis.…”