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Pd20Pt20Cu20Ni20P20高熵非晶合金蠕变机理研究

CREEP MECHANISM OF Pd20Pt20Cu20Ni20P20 HIGH ENTROPY AMORPHOUS ALLOY

  • 摘要: 以Pd20Pt20Cu20Ni20P20高熵非晶合金作为研究载体, 通过蠕变循环加载及循环加载-回复实验, 着重考察了蠕变变形、准稳态蠕变速率、蠕变应力指数和弛豫时间分布谱演变规律, 系统探索了温度、循环加载及回复时间对其蠕变行为的影响. 研究结果表明, 该合金的蠕变行为明显依赖于温度和应力, 低温及低应力环境下合金表现出较好的抗蠕变性能, 主要以弹性变形为主. 随着温度增加, 合金抗蠕变能力减弱, 黏弹性(黏塑性)变形成为主导. 循环应力在低温下对蠕变变形影响较小, 而在高温下其影响显著, 表明循环载荷能加剧蠕变行为, 导致准稳态蠕变速率上升. 回复时间对合金的瞬时弹性变形和滞弹性变形有显著影响, 但对黏塑性变形的调节作用有限. 卸载后合金变形能力逐渐增强, 蠕变抑制得到缓解. 此外, 变形单元弛豫时间的广泛分布和对循环应力的敏感反应, 揭示了蠕变机制的复杂性和多时间尺度的结构演化.本研究通过系统的实验和分析, 深化了对高熵非晶合金蠕变行为及其调控机制的理解. 为高性能高熵非晶合金的设计和应用提供了重要的理论依据和实践指导, 对未来开发更具抗蠕变能力的先进材料具有一定意义.

     

    Abstract: In the current work, a Pd20Pt20Cu20Ni20P20 high-entropy metallic glass was selected as the model system to explore the deformation mechanisms under different loading conditions. Creep cyclic loading and cyclic loading-unloading experiments were carried out to elucidate the deformation mechanisms, steady-state creep rate, creep stress index, and the evolution of relaxation time spectra. This study systematically investigated the effects of temperature, cyclic loading, and recovery time on the creep behavior of this high-entropy metallic glass, offering a comprehensive analysis of its response to various stress and thermal conditions. Our findings revealed that the creep behavior of the alloy significantly depended on both temperature and stress, exhibiting superior creep resistance under low temperature and stress conditions. In these environments, the deformation was primarily dominated by elastic deformation. However, with the increase of temperature, the resistance to creep progressively weakened, and viscoelastic (viscoplastic) deformation became the dominant deformation mechanism. Notably, the impact of cyclic stress on creep deformation was found to be negligible at low temperatures but became markedly significant at higher temperatures. This suggests that cyclic loading exacerbated creep behavior, leading to a notable increase in the steady-state creep rate as temperature rises. Recovery duration markedly affected the instantaneous elastic deformation and viscoelastic deformation, albeit with a limited modulatory capacity on viscoelastic deformation. After unloading, the deformation capacity of model alloy gradually increases, alleviating creep inhibition. Furthermore, the wide distribution of relaxation times and their sensitive response to cyclic stress highlighted the complexity of the creep mechanism and the evolution of structures across multiple time scales. This study, through systematic experiments and analysis, deepened the understanding of the creep behavior and control mechanisms of high-entropy metallic glasses. It provides important theoretical foundations and practical guidance for the design and application of high-performance high-entropy metallic glasses and holds significance for the future development of advanced materials with enhanced creep resistance.

     

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