An experimental investigation on the notch toughness of Cu-Zr-based bulk metallic glasses with in-situ crystallization

摘要

Abstract The notch toughness of wear-resistant Cu43Zr43Al7Be7 bulk metallic glasses (BMGs) with in-situ crystallization is investigated. Using different cooling rates during copper mold casting and a post-cast anneal, the amount of crystallization is controlled and varied. The notch toughness correlates most closely with the composition of the remaining amorphous matrix, as measured by energy-dispersive X-ray spectroscopy (EDS). As the matrix composition shifts further away from the designed high-glass forming composition, the toughness decreases. The sample with a matrix composition that closely matches Cu43Zr43Al7Be7 is shown to be the toughest, with a notch toughness of 54MPa-m1/2. X-ray diffraction (XRD), EDS and electron backscatter diffraction (EBSD) were used to identify the metastable crystalline phase as Cu3Zr5Al2(+Be) with a cubic Fm 3 ? m structure. Furthermore, the crystalline phases are shown to be harder than the glassy matrix, and therefore likely contribute to the high wear-