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作为潜在的功能及结构材料, 高熵非晶合金在凝聚态物理和力学领域引起广泛的研究兴趣. 高熵非晶合金宏观力学性能与微观结构非均匀性之间的关联是当前重要的科学问题之一. 本文选取非晶形成能力良好的Pd 42.5Cu 30Ni 7.5P 20非晶合金和Pd 20Pt 20Cu 20Ni 20P 20高熵非晶合金作为模型体系, 借助于动态弛豫行为及应力松弛实验建立了温度和物理时效对非晶合金高温变形机制与微观结构非均匀性之间的关联. 研究结果表明Pd基非晶合金表现出“肩膀峰” β弛豫形式. 玻璃转变温度以下物理时效非晶合金体系原子移动性导致 β弛豫肩膀峰往更高的温度迁移. 在应力松弛过程中, 由于高构型熵的引入降低吉布斯自由能, 这是高熵非晶合金具有较高激活能的原因. 高熵非晶合金更难被激活, 需要突破更高的能量势垒. 物理时效时间增加, 高熵非晶合金流变单元更小, 这也得益于多主元高熵非晶合金慢扩散效应. 高熵非晶合金激活体积的改变在物理时效下应力松弛过程中的敏感性低于对应的非晶合金.As a potential functional and structural material, high-entropy metallic glasses have aroused tremendous research interest in condense matter physics and mechanics. The correlation between macroscopic mechanic properties and microstructure heterogeneity of high-entropy metallic glasses is one of the most important scientific issues in glassy solids. In the present research, Pd 42.5Cu 30Ni 7.5P 20metallic glass and Pd 20Pt 20Cu 20Ni 20P 20high-entropy metallic glass are selected as the model alloys. Dynamic mechanical analysis (DMA) and stress relaxation are used to investigate the influences of temperature and physical aging on dynamic mechanical relaxation process and microstructure heterogeneity of the model alloys. The dynamic mechanical analysis results demonstrate that the Pd 42.5Cu 30Ni 7.5P 20metallic glass and Pd 20Pt 20Cu 20Ni 20P 20high-entropy metallic glass both exhibit evident βrelaxation process. In addition, the atomic mobility of model alloys is reduced in these processes, and the βrelaxation shifts toward higher temperatures. In the stress relaxation process, the Gibbs free energy is reduced due to the high configurational entropy. This is the potential reason that high-entropy metallic glass possesses higher activation energy. In parallel, high-entropy metallic glass is more difficult to activate and needs to break through a higher energy barrier. With the increase of physical aging time, the flow unit in high-entropy metallic glass becomes smaller. This also benefits from the high-entropy effects that bring sluggish diffusion into high-entropy metallic glass. The change of activation volume under physical aging of high-entropy metallic glass is less sensitive to stress relaxation than that of metallic glass.
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