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徐宗睿, 郝奇, 张浪渟, 乔吉超. 基于准点缺陷理论探索非晶合金蠕变机制. 力学学报, 2022, 54(6): 1590-1600. DOI: 10.6052/0459-1879-22-059
引用本文: 徐宗睿, 郝奇, 张浪渟, 乔吉超. 基于准点缺陷理论探索非晶合金蠕变机制. 力学学报, 2022, 54(6): 1590-1600. DOI: 10.6052/0459-1879-22-059
Xu Zongrui, Hao Qi, Zhang Langting, Qiao Jichao. Probing into the creep mechanism of amorphous alloy based on quasi-point theory. Chinese Journal of Theoretical and Applied Mechanics, 2022, 54(6): 1590-1600. DOI: 10.6052/0459-1879-22-059
Citation: Xu Zongrui, Hao Qi, Zhang Langting, Qiao Jichao. Probing into the creep mechanism of amorphous alloy based on quasi-point theory. Chinese Journal of Theoretical and Applied Mechanics, 2022, 54(6): 1590-1600. DOI: 10.6052/0459-1879-22-059

基于准点缺陷理论探索非晶合金蠕变机制

PROBING INTO THE CREEP MECHANISM OF AMORPHOUS ALLOY BASED ON QUASI-POINT THEORY

  • 摘要: 作为典型多体相互作用非平衡体系, 如何明晰非晶合金多场耦合激励下变形机制, 建立非晶合金变形行为、流动特性与微观结构特征本征关联始终是非晶合金力学性能的重要研究内容. 本文以具有显著 \beta 弛豫行为的La56.16Ce14.04Ni19.8Al10非晶合金作为研究载体, 通过开展宽温度应力窗口蠕变实验, 着重考查了蠕变柔量、准稳态蠕变速率、特征弛豫时间、蠕变应力指数及蠕变激活能演变规律, 系统研究了非晶合金蠕变行为与蠕变机制. 基于准点缺陷理论分析了非晶合金蠕变行为由弹性向黏弹性及黏塑性逐步转变的过程, 从微观结构演化角度构建了非晶合金蠕变行为完整物理图像. 研究结果表明, 非晶合金高温蠕变行为是一典型热力耦合、非线性过程, 其潜在蠕变机制受控于温度、应力与加载时间. 应力较低时, 非晶合金蠕变机制对应于热激活单粒子流动. 应力较高时, 蠕变机制则对应于应力诱导局部剪切变形增强与温度诱导原子扩散等复杂耦合过程. 非晶合金蠕变变形过程所涉及弹塑性转变源于非晶合金准点缺陷激活、微剪切畴经热力耦合激励形核长大、扩展与不可逆融合.

     

    Abstract: As a typical multi-body interaction and non-equilibrium system, how to clarify the deformation mechanism under multi-field coupling stimuli and then establish the intrinsic correlation among the deformation behavior, flow characteristics and microstructure evolution of amorphous alloys keep the fundamental topic. In the current work, a prototypical La56.16Ce14.04Ni19.8Al10 amorphous alloy which shows a pronounced slow \;\beta relaxation process was selected as the model system. Series of creep experiments of the amorphous alloy over wide temperature and stress range were carried out. Evolution of creep compliance J , quasi steady-state strain rate \dot\varepsilon _s , characteristic relaxation time \tau , stress index n along with the apparent activation energy for creep Q_\rmappwere systematically investigated in order to probe into the deformation mechanism involved in the creep process of amorphous alloys. In parallel, a gradual transition of deformation mode from elasticity to viscoelasticity and viscoplasticity of amorphous alloys during creep was analyzed. In the framework of the quasi-point defects theory, a complete picture delineating the deformation process of amorphous creep was probed from the perspective of microstructure evolution. The results demonstrated that the creep deformation of amorphous alloy is a typical thermo-mechanical coupling and nonlinear mechanics process, which could be affected by experimental temperature, applied stress and loading time. The creep mechanism of amorphous alloy is dominated by the diffusion which is related to thermal particle flow when the applied stress is lower. On the other hand, when the stress is higher, the creep mechanism corresponds to more complicated synergistic actions consisting of both stress-induced collective rearrangements of atoms and temperature-induced thermal activation. In addition, the underlying physical background of the elastic-plastic transition of the amorphous alloy during creep deformation was described, which is correlated to the initiation of quasi-point defects as well as the formation, expansion and coalescence process of sheared micro-domains under thermo-mechanical stimuli.

     

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