A Series of Zr-Based Bulk Metallic Glasses with Room Temperature Plasticity

A group of plastic Zr-Al-Ni-Cu bulk metallic glasses (BMGs) with low Zr content was developed and their thermal and mechanical properties were investigated. The results show that these Zr-based BMGs have a single crystallization event for all heating rates in the studied temperature region. The glass transition temperature T-g decreases with increasing Zr content for all heating rates. There are two melting procedures for the BMGs whose Zr content is less than 52 at %, while three melting procedures for the other Zr-based BMGs. The second melting procedure is split into two melting procedures for Zr52.5Al12.2Ni12.6Cu22.7 and Zr53Al11.6Ni11.7Cu23.7 BMGs, while the first melting procedure is split into two melting procedures for the other BMGs. The activation energy decreases with increasing sensitivity index beta for the studied Zr-based BMGs. The plastic strain epsilon(p) is in the region of 0.2%-19.1% for these Zr-based BMGs. Both yield strength sigma(y) and fracture strength sigma(f) are smallest for Zr55Al8.9Ni7.3Cu28.8 BMG whose epsilon(p) is largest among all studied Zr-based BMGs and reaches up to 19.1%. In addition, the mechanism for the large difference of the plasticity among the studied Zr-based BMGs is also discussed.