In this study, a series of Al₅Nb_(25-x)Ti35Zr₃₅Mo_x (x=0, 5, 10, 15 at% (atomic fraction), defined as Mo0, Mo5 Mo10 and Mo15, respectively) novel refractory high entropy alloys (RHEAs) was prepared by vacuum arc furnace. The effects of Mo content on the microstructure and mechanical properties of the alloy were systematically studied. The results show that the as-cast alloys exhibited a single BCC structure. The degree of lattice distortion increased as Mo content increased in the as-cast alloys. Additionally, Mo addition significantly refined the grain size. The room temperature yield strength of the alloys increased dramatically from 908 MPa for Mo0 alloy to 1593 MPa for Mo15 alloy, accompanied by a notable loss in ductility for Mo15. The solid solution strengthening contributs increasing significantly with Mo content increases. The addition of Mo induces significant lattice distortion, thereby enhancing the solid solution strengthening effect that primarily account for the yield strength improvement. At 800°C compression, the yield strength increased by 252.6% from 152 MPa to 536 MPa as the Mo content increasing from 0 to 15 at.%. All the four alloys demonstrated outstanding high-temperature ductility (>50% strain). There is no phase transition occurs in the Al₅Nb_(25-x)Ti₃₅Zr₃₅Mo_x alloys during high-temperature deformation process, maintaining a single BCC structure.

中文翻译：

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Al5Nb（25-x）Ti35Zr35Mox 高熵合金的显微组织和力学性能

本研究采用真空电弧炉制备了一系列 Al ₅ Nb _(25-x) Ti35Zr ₃₅ Mo _x （x=0， 5， 10， 15 at%（原子分数），分别为 Mo0、Mo5、Mo10 和 Mo15）新型难熔高熵合金 （RHEAs）。系统研究了 Mo 含量对合金微观组织和力学性能的影响。结果表明，铸态合金表现出单一的 BCC 结构。铸态合金中 Mo 含量的增加，晶格变形的程度增加。此外，Mo 的添加显着细化了晶粒尺寸。合金的室温屈服强度从 Mo0 合金的 908 MPa 急剧提高到 Mo15 合金的 1593 MPa，同时 Mo15 的延展性也明显下降。固溶体强化的作用随着 Mo 含量的增加而显著增加。Mo 的添加会引起显着的晶格畸变，从而增强固溶强化效果，这主要是提高屈服强度的主要原因。在 800°C 压缩时，随着 Mo 含量从 0 增加到 15，屈服强度从 152 MPa 增加到 536 MPa，屈服强度增加了 252.6%。所有四种合金都表现出出色的高温延展性（>50% 应变）。在高温变形过程中，Al ₅ Nb _(25-x) Ti ₃₅ Zr ₃₅ Mo _x 合金不会发生相变，保持单一的 BCC 结构。