非晶合金中弹性模量特征及结构状态演化分析
Analysis of Elastic Modulus Characteristics and Structural State Evolution in Amorphous Alloys
-
摘要: 非晶态固体物理老化对于理解其玻璃转变, 力学变形和晶化行为至关重要, 核心在于如何构建老化模型以帮助理解弛豫机制和预测材料力学, 物理性能的演化. 本文通过对Zr46Cu46Al8 非晶合金室温到过冷液相区剪切模量测试和动态力学参量测试, 探究了非晶合金升温过程中的结构状态演化. 本文假设剪切模量变化量正比于缺陷浓度变化, 进而计算获得缺陷浓度随温度演化. 当前工作考虑物理老化过程中缺陷浓度向平衡态演化服从一阶动力学, 并假设特征时间的Arrhenius温度依赖性, 半定量计算了非晶合金缺陷浓度的温度依赖性. 研究结果表明, 等构型状态下晶态及非晶态合金剪切模量均随温度近似线性减小. 铸态非晶合金剪切模量随温度演化表现为三个典型区域: 深玻璃态等构型条件下剪切模量近似线性降低, 中间温度区域老化导致剪切模量相对升高和玻璃转变温度之上剪切模量急剧减小. 剪切模量弛豫与缺陷浓度演化密切相关, 当前基于一阶动力学所构建老化模型计算所得缺陷浓度演化与基于剪切模量数据所得缺陷演化数据吻合. 此外基于动态力学参量的温度依赖性分析, 分析了老化对复模量演化的影响, 指出当前体系中的过剩尾行为源于老化导致的模量变化和α弛豫谱特征变化, 而非一般意义上的次级弛豫行为.Abstract: The physical aging of amorphous solids is crucial for understanding their glass transition, mechanical deformation, and crystallization behavior, with the core focus on constructing aging models to elucidate relaxation mechanisms and predict the evolution of their mechanical and physical properties. This study investigates the structural state evolution of Zr46Cu46Al8 amorphous alloy during heating from room temperature to the supercooled liquid region by testing its shear modulus and dynamic mechanical parmaters. The study assumes that changes in shear modulus are proportional to variations in defect concentration and derives the temperature-dependent evolution of defect concentration. The current work considers that defect concentration evolution towards equilibrium during physical aging follows a first-order kinetic equation, assuming an Arrhenius temperature dependency for the characteristic time. A semi-quantitative calculation of the temperature dependence of defect concentration in amorphous alloys is provided. Results show that, under an isoconfigurational state, the shear modulus of both crystalline and amorphous alloys approximately decreases linearly with temperature. For as-cast amorphous alloys, the temperature dependence of the shear modulus exhibits three distinct regions: a nearly linear decrease in the deep glassy state under isoconfigurational conditions, a moderate temperature range where aging induces a relative increase in the shear modulus, and a rapid decline in the shear modulus above the glass transition temperature. The relaxation of the shear modulus is closely related to the evolution of defect concentration in non-equilibrium amorphous alloys. The defect concentration evolution calculated using a first-order kinetic aging model aligns well with that derived from shear modulus data. Furthermore, based on the temperature dependence of dynamic mechanical parameters, the impact of aging on the evolution of complex modulus was analyzed, revealing that the excess wing behavior in the present system is attributable to changes in the α relaxation spectrum caused by aging, rather than conventional secondary relaxation processes.