Applicability of Pre-Plastic Deformation Method for Improving Mechanical Properties of Bulk Metallic Glasses.

Pre-plastic deformation (PPD) treatments on bulk metallic glasses (BMGs) have previously been shown to be helpful in producing multiple shear bands. In this work, the applicability of the PPD approach on BMGs with different Poisson's ratios was validated based on experimental and simulation observations. It was found that for BMGs with high Poisson's ratios (HBMGs, e.g., Zr 56 Co 28 Al 16 and Zr 46 Cu 46 Al 8 ), the PPD treatment can easily trigger a pair of large plastic deformation zones consisting of multiple shear bands. These PPD-treated HBMGs clearly display improved strength and compressive plasticity. On the other hand, the mechanical properties of BMGs with low Poisson's ratios (LBMG, e.g., Fe 48 Cr 15 Mo 14 Y 2 C 15 B 6 ) become worse due to a few shear bands and micro-cracks in extremely small plastic deformation zones. Additionally, for the PPD-treated HBMGs with similar high Poisson's ratios, the Zr 56 Co 28 Al 16 BMG exhibits much larger plasticity than the Zr 46 Cu 46 Al 8 BMG. This phenomenon is mainly due to more defective icosahedral clusters in the Zr 56 Co 28 Al 16 BMG, which can serve as nucleation sites for shear transformation zones (STZs) during subsequent deformation. The present study may provide a basis for understanding the plastic deformation mechanism of BMGs.