A Centimeter-Size High Toughness Zr-Cu-Al-Nb Bulk Metallic Glass with Nano-Crystallization and Phase Separation

Abstract

In this paper, a centimeter-size Zr-Cu-Al-Nb bulk metallic glass (BMG) with high notch toughness of 107±13 MPa∙m0.5 was designed and fabricated by copper mold casting. With 1% Nb substitution for Zr in Zr48Cu45Al7 glass forming alloy, the glass forming ability (GFA) and toughness of the BMG were enhanced significantly. The coexistence of nano-crystallization and phase separation in the glassy matrix was observed in Zr47Cu45Al7Nb1, which would possibly lead to the high toughness of this alloy due to the easy and populous nucleation of shear bands and the increasing resistance of shear band propagation. The influences of nano-crystallization and phase separation on the toughness of BMGs are discussed in detail. The strategy utilized in this study provides a novel approach in search for new BMGs with high toughness and good GFA.