Microstructural Evolution and Mechanical Properties of Zr-Cu-Ni-Al Bulk Metallic Glasses by the Bridgman Solidification

The microstructural evolution was experimentally studied at a withdrawal velocity between 6 and 0.1 mm/s by a Bridgman technique in Zr_51.7Cu₃₀Ni_8.3Al₁₀. Our results indicate that the Zr_51.7Cu₃₀Ni_8.3Al₁₀ alloy can be considered as the ZrCu-Zr₂Cu pseudo-binary eutectic system, and the glass-forming ability (GFA) is correlated with the (L → ZrCu + Zr₂Cu) pseudo-binary eutectic reaction. This understanding has important implications and guidance for designing and fabricating new Zr-Cu-Ni-Al bulk metallic glasses (BMGs) with superior glass formation. Moreover, compressive tests were also performed on these samples. The results show that as the precipitation of crystal, plastic strain decreases. It indicates that the precipitated crystal cannot block the fast propagation of the localized shear bands and the macroscopically brittle failure.