Herein, extensive computational modelling and experimental measurements to explore the effects of partial substitution of Ta with Ti in a series of TiTaNbZrMo ( = 0.25, 0.5, 0.75, 1) RHEAs to improve its mechanical properties. Density-functional theory (DFT) calculations predicted that a BCC phase is stable for these alloys and its stability improves with increasing Ta concentration. CALPHAD calculations and experimental measurements revealed that RHEA alloys consist of two BCC phases (BCC1 and BCC2). Substitution of Ti atoms with Ta atoms was found to stabilize the BCC1 and increases its volume fraction. Ta enrichment also resulted in a coarser microstructure with increased Ta segregation in BCC1, and Zr segregation in BCC2 phases which resulted in an increase in the lattice parameters for both phases. DFT calculations predicted an improvement in the magnitudes of the elastic properties, bulk hardness and strength of the RHEAs by increasing Ta concentration, which is also supported by experimental results. Crystal orbital Hamiltonian population (COHP) and density of states (DOS) calculations indicated that the improvement in properties with increasing Ta content was due to the formation of strong directional metallic bonds and a higher percentage of occupied bonding states. Existing research demonstrates that in total joint arthroplasty (TJA), ceramics and CoCrMo-alloy bearing surfaces can be replaced with TiTaNbZrMo RHEAs due to their excellent mechanical properties, wear resistance corrosion resistance, and biocompatibility. However, the preliminary advantages of the Ta-rich (TiTa(NbZrMo)) alloy over the equiatomic TiTaNbZrMo RHEA in mechanical properties can be a potential candidate for articulating surfaces.

中文翻译：

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富TaTiTaNbZrMo难熔高熵合金的相稳定性和力学性能

在此，通过广泛的计算模型和实验测量来探索在一系列 TiTaNbZrMo (= 0.25, 0.5, 0.75, 1) RHEA 中用 Ti 部分替代 Ta 的效果，以提高其机械性能。密度泛函理论 (DFT) 计算预测，这些合金的 BCC 相是稳定的，并且其稳定性随着 Ta 浓度的增加而提高。 CALPHAD 计算和实验测量表明，RHEA 合金由两个 BCC 相（BCC1 和 BCC2）组成。发现用 Ta 原子取代 Ti 原子可以稳定 BCC1 并增加其体积分数。 Ta 富集还导致微观结构变得更粗，BCC1 相中的 Ta 偏析增加，BCC2 相中的 Zr 偏析增加，从而导致两相的晶格参数增加。 DFT 计算预测通过增加 Ta 浓度可以显着提高 RHEA 的弹性性能、体积硬度和强度，这也得到了实验结果的支持。晶体轨道哈密顿群 (COHP) 和态密度 (DOS) 计算表明，随着 Ta 含量的增加，性能的改善是由于形成了强方向性金属键和更高百分比的占据键态。现有研究表明，在全关节置换术（TJA）中，陶瓷和CoCrMo合金轴承表面可以用TiTaNbZrMo RHEA替代，因为它们具有优异的机械性能、耐磨耐腐蚀性和生物相容性。然而，富钽 (TiTa(NbZrMo)) 合金在机械性能方面优于等原子 TiTaNbZrMo RHEA 的初步优势可能是铰接表面的潜在候选者。