Deformation behavior of Zr-Al-Cu-Ni-Sn metallic glasses

摘要

A highly deformable Zr-AI-Cu-Ni-Sn alloy system without any catastrophic failure has been developed and the underling mechanism for exceptional plasticity has been investigated in terms of structural characteristics and atomic movement kinetics. The as-cast Zr_(61.7)Al_8Ni_(13)Cu_(17)Sn_(0.3) bulk metallic glass has many local nanoscale ordering features. They can play a critical role in nucleating abundant shear bands that sufficiently accommodate global plasticity. During deformation at room temperature, the ordered regions do not grow, providing a structural stability, possibly from the sluggish atomic movement kinetics. Thermal activation energy for crystallization of the Zr_(61.7)Al_8Ni_(13)Cu_(17)Sn_(0.3) alloy is estimated as 3.96 eV, which is about 2.8 times higher than that of the Z_(41.2)Ti_(13.8)Cu_(12.5)Ni_(10)Be_(22.5) alloy [Vitreloy 1 (Vitl)] and the dynamic mass flow rate is around 10 times slower than that of Vitl. A thermomechanical estimation of compressive strain rates under constant stress shows a sluggish atomic movement upon the addition of Sn.