The Microstructure of Zr-Based Bulk Metallic Glass and Glass Matrix Composite

This study describes the microstructure of a Zr-based alloy (Zr63.36Cu17.22Ni11.47Al7.95, at.%) under different cooling conditions. The Zr-based alloy can obtain completely amorphous structure, amorphous/nanocrystalline droplet and amorphous/crystalline composite structure by fast to slow cooling rate. It is interesting in the amorphous/nanocrystalline droplet composite that the average compositions of the droplet phase and amorphous matrix phase were same as the original alloy composition and the contrasts of BEI (back scatting image) were different. The droplet phase formed with (Al,Ni)2Zr3, and Zr2Ni(Al,Cu) nanocrystalline structures based on the analysis of XRD (X-ray diffractometry), EBSD (electron backscatter diffraction) and TEM (transmission electron microscopy). And Zr2Ni(Al,Cu) nanocrystalline phase transfers to the Zr2Cu(Al,Ni) phase after thermal treatment. The equilibrium phases of the alloy have been identified as Zr2Ni phase, Zr2Cu phase, Al2NiZr6 phase and τ3 (Zr51Cu28Al21, at.%) phase which reach four phases equilibrium at 1,073 K for one week.