纳米晶化对锆基非晶合金动态压缩性能的影响

Zr-based amorphous alloys are characterized by high glass forming ability, high thermal stability and excellent mechanical properties. The amorphous alloys in thermodynamic metastable state have the tendency to change to metastable state with lower energy or even crystal structure in equilibrium state under certain temperature or pressure conditions. At present, few researches have been conducted on the mechanical behavior of partially crystallized Zr-Cu-Ni-Al-Nb amorphous alloys, especially the fracture behavior under dynamic loading. In this work, as-cast Zr-Cu-Ni-Al-Nb amorphous alloy was annealed to accomplish different levels of nano-crystallization by controlling holding time. DSC, XRD, HRTEM, SEM, quasi-static and dynamic compression tests were utilized to research the effect of nanocrystallization on compressive strength and fracture mechanism of Zr-based amorphous alloy under different strain rates. The results indicated that the volume fraction and size of nanoscale crystalline phase inside Zr-based amorphous alloy increased with the increasing of annealing holding time. The compressive strength of annealed Zr-based amorphous alloy increased first and then decreased with the increase of holding time. The variation of strain rates also affected the compressive strength, which decreased when the strain rate increased from 1×10^-3 s^-1 to 1×10³ s^-1, and increased when the strain rate continually increased to 3×10³ s^-1. Different degrees of nano-crystallization had an impact on the fracture characteristics of Zr-based amorphous alloy. As the degree of crystallization increased, the fracture morphology of compression samples changed from vein-like patterns to quasi-cleavage features and then to river patterns.