退火与“机械退火”对金属玻璃结构和力学性能的影响

金属玻璃是一种新型亚稳态金属材料,具有一系列优良的物理、化学和力学性能。然而在高温或室温长期使用条件下,金属玻璃易于转变为更稳定、更低能量状态的晶体材料,已成为限制其广泛应用的瓶颈之一。研究金属玻璃的退火对其结构、力学性能的影响具有重要的意义。文章综述了常规退火与"机械退火"对大块金属玻璃的结构和力学性能的影响。研究发现:在玻璃化转变温度以下退火时,密度、剪切波速度、纵波速度和弹性模量随退火时间的增加而增加,这是由于在结构上不同程度的原子重排所致;大块金属玻璃在低于屈服强度的恒定应力下"机械退火"密度增加;卸载载荷室温下时效处理超过30天后,屈服强度和断裂强度均降低,并且在塑性阶段锯齿状塑性流动的幅度增加。这个结果可能对于深入理解大块金属玻璃的结构和塑性变形具有一定的指导作用。

Effect of annealing and mechanical-annealing on the structure and mechanical properties of metallic glass#br#

Metallic glasses are a kind of novel metastable metallic materials with a series of excellent physical, chemical and mechanical properties. However, long-term use under high temperature or even at room temperature, metallic glasses are easy to transform into crystalline materials with a more stable and lower energy state, which is one of the bottlenecks limiting its wide applications. It is of great significance to investigate the influence of annealing of metallic glasses on its structure and mechanical properties. We reviewed the effects of conventional annealing and mechanical-annealing on the structure and mechanical properties of bulk metallic glass. It has been found that the density, shear wave velocity, longitudinal wave velocity and elastic modulus increased with annealing time below the glass transition temperature due to atomic rearrangement at a certain degree. While under mechanical annealing, bulk metallic glass had a tendency of density increase at a constant stress below the yield strength. After aging treatment at room temperature for more than 30 days, both the yield strength and fracture strength decreased, and the amplitude of the serrated plastic flow increased during the plastic phase. This result may have some guiding role in understanding the structure and plastic deformation of bulk metallic glasses.