The unique high-entropy and sluggish diffusion effects of amorphous high-entropy alloys endow them with excellent thermal stability and plastic deformation. In this work, the near-equiatomic TaTiZr amorphous medium-entropy alloy (AMEA) was prepared via the magnetron sputtering to investigate the microstructural thermostability and nanoindentation creep behavior. Thermal annealing below the glass transition temperature gave rise to the microstructural heterogeneity due to the positive mixing enthalpy in TaTiZr AMEA, which became increasingly enhanced with raising the annealing temperature. Correspondingly, there appeared a monotonic increase in hardness as well as the elastic/shear modulus, yet a reduction in strain-rate sensitivity m or an increment in shear transformation zone volume with annealing temperature. Meanwhile, the indentation morphology measured by atomic force microscope exhibited a significant transformation from pile-up to sink-in, demonstrating the degradation of plastic deformability with enhancing the microstructural heterogeneity. Based on the relaxation time spectra for Maxwell-Voigt model, the microstructural heterogeneity can restrain the activation of internal defects associated with the operation of flow units during creeping, further triggering the strain-strengthening behavior and improved creep resistance in the annealed samples. This work provides significant guidance for the structural design of high-performance amorphous alloys.

中文翻译：

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热退火影响非晶 TaTiZr 中等熵合金的微观组织演变和蠕变行为


非晶态高熵合金独特的高熵和缓慢扩散效应赋予了它们优异的热稳定性和塑性变形能力。在本工作中，通过磁控溅射制备了近等原子 TaTiZr 非晶态中等熵合金 （AMEA），以研究其微观结构热稳定性和纳米压痕蠕变行为。由于 TaTiZr MEA 中的正混合焓，低于玻璃化转变温度的热退火引起了微观结构异质性，这种异质性随着退火温度的升高而越来越增强。相应地，硬度和弹性/剪切模量出现单调增加，但应变速率敏感性 m 降低或剪切变形区体积随退火温度增加。同时，原子力显微镜测量的压痕形貌表现出从堆积到下沉的显着转变，证明了塑性变形能力的降解，同时增强了微观结构的异质性。基于 Maxwell-Voigt 模型的弛豫时间谱，微观结构异质性可以抑制蠕变过程中与流动装置运行相关的内部缺陷的激活，进一步触发退火样品的应变强化行为和提高的抗蠕变性。这项工作为高性能非晶合金的结构设计提供了重要的指导。