Crystallization and Glass Formation in Electron and Laser Beam Irradiated Cu-Zr Alloys

摘要

Four Cu-Zr alloys, Cu sub 56 Zr sub 44 , Cu sub 50 Zr sub 50 , Cu sub 47 Zr sub 53 , and Cu sub 33 Zr sub 67 , were surface melted with electron and pulsed laser beams to compare their kinetics of nucleation, growth and glass formation. It was observed that the ease of glass formation increased in the order: Cu sub 33 Zr sub 67 , Cu sub 47 Zr sub 53 , Cu sub 56 Zr sub 44 , and Cu sub 50 Zr sub 50 . The nucleation and regrowth produced different metastable phases. At the equiatomic composition, the preferred phase is a CsCl-type (B2) BCC structure. As the composition deviates from this, the preferred phase is either orthorhombic or tetragonal with a much larger unit cell not previously reported in the literature. The maximum growth velocity of these metastable phases was found to be about 0.025 m/s. The slow kinetics are responsible for the ease of glass formation in these systems. 4 refs., 7 figs., 2 tabs. (ERA citation 13:015093)