Dual specimen-size dependences of plastic deformation behavior of a traditional Zr-based bulk metallic glass in compression

The plastic deformation behavior of a traditional BMG with the composition of Zr65Cu17.5Ni10Al7.5 was investigated in compression using the precursory-specimens with different casting sizes and hence different initial states. With increasing the mechanical-testing size of specimen, it is demonstrated that more pronounced action of elastic recoveries of testing machine and specimen led to a decrease in plasticity because of larger shear-strain was introduced in shear bands. Furthermore, for the specimens with the same mechanical-testing size, initial free-volume reduction with increasing the casting size of precursory-specimen also led to a degradation of plasticity as higher free-volume was required for higher shear band emission rate. Even the traditional BMG can be ductile as the casting size and mechanical-testing size of specimen were concurrently decreased to a certain extent. The understanding of the dual specimen-size dependences of plastic deformation capability of BMGs is helpful for the potential and reasonable engineering applications of BMGs.