锆基非晶合金的动态弛豫和应力松弛  

Dynamical relaxation and stress relaxation of Zr-based metallic glass

作　　者：黄蓓蓓 郝奇 吕国建 乔吉超 Huang Bei-Bei;Hao Qi;Lyu Guo-Jian;Qiao Ji-Chao(School of Materials Science and Engineering,Northwestern Polytechnical University,Xi’an 710072,China;School of Mechanics,Civil Engineering and Architecture,Northwestern Polytechnical University,Xi’an 710072,China)

机构地区：[1]西北工业大学材料学院,西安710072 [2]西北工业大学力学与土木建筑学院,西安710072

出　　处：《物理学报》2023年第13期142-150,共9页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:51971178,52271153);陕西省杰出青年基金(批准号:2021JC-12)资助的课题。

摘　　要：非晶合金动态弛豫、变形和微观结构非均匀性之间的关联是非晶态物理领域重要研究内容之一.本文选取玻璃形成能力优良,热稳定性好的Zr_(48)(Cu_(5/6)Ag_(1/6))_(44)Al_(8)块体非晶合金作为研究载体,借助于动态力学分析及应力松弛实验探究了温度和结构弛豫对非晶合金动态弛豫和变形行为的影响.研究结果表明非晶合金动态弛豫行为对温度极其敏感,随温度升高表现为等构型、老化、玻璃转变和晶化4个阶段.基于玻璃转变温度之下等温测试,结构弛豫行为导致非平衡高能量状态非晶合金向低能量状态迁移,内耗随时间演化规律可用Kohlrausch-Williams-Watts(KWW)扩展指数方程描述.此外,基于KWW方程和激活能谱等方法分析了模型合金应力松弛过程中非均匀结构激活,该过程涉及弹性变形向非弹性变形的转变.由于非晶合金存在微观尺度的结构非均匀性与能量起伏,变形单元的激活并非为单一特征时间,而是服从一定分布.通过考虑对数时间尺度和变形单元激活的特征时间分布分别为对称Gauss分布和非对称Gumbel分布,可重构应力松弛响应的非均匀激活过程.The relationship among dynamic relaxation,deformation and microstructural heterogeneity of amorphous alloy is one of the important research contents in the field of amorphous physics.In this paper,we utilize Zr_(48)(Cu_(5/6)Ag_(1/6))_(44)Al_(8) bulk amorphous alloy with excellent glass forming capability and good thermal stability as a research carrier,and investigate the effects of temperature and structural relaxation on dynamic relaxation and deformation behavior through dynamic mechanical analysis and stress relaxation experiments.The results show that the dynamic relaxation spectrum of the model alloy is sensitive to temperature,showing four stages as the temperature increases,namely,iso configuration,aging,glass transition and crystallization.Based on the isothermal measurement of dynamic mechanical parameters under the glass transition temperature,the structural relaxation causes the amorphous alloy to migrate from the non-equilibrium high energy state to the low energy state,and the evolution of internal friction with aging time can be described by Kohlrausch-Williams-Watts(KWW)stretched exponential function.In addition,based on the KWW equation and activation energy spectrum,the activation of heterogeneous structure in the stress relaxation process of model alloy is analyzed,which involves the transformation from elastic deformation to nonelastic deformation.Owing to the microstructural heterogeneity and energy fluctuations in amorphous alloys,the activation of deformation units is not a single characteristic time,but follows a certain distribution.By considering that the characteristic time distribution of activation of deformation units is symmetric Gauss distribution or asymmetric Gumbel distribution on a logarithmic time scale,the heterogeneous activation process in stress relaxation response can be reconstructed.

关 键 词：非晶合金 动态弛豫 应力松弛 微观结构非均匀性 

分 类 号：TG139.8[一般工业技术—材料科学与工程]