Improvement of plasticity in Pd containing Zr-Al-Ni-Cu bulk metallic glass by deformation-induced nano structure change

Abstract

We have prepared Zr-AI-Ni-Cu-Pd bulk metallic glasses (BMGs) cast in an ambient Ar atmosphere, in which the cooling effect is enhanced. The Zr 65Al7.5Ni10Cu17.5-xPdx (x = 1-5) BMGs exhibit a good plasticity during the compressive deformation process. A significant plasticity of 6% plastic strain is obtained in the Zr65Al7.5Ni10Cu12.5Pd5 BMG, where the deformation mode with multi shear bands appears near the fracture surface. Nanocrystalline particles are arranged in a band-like formation in the glassy matrix around the multi shear bands, indicating the restraint of shear band propagation owing to the dynamic precipitation of the nanocrystals. The unrelaxed structure owing to the higher cooling rate in the present condition may also contribute to the good plasticity. © 2008 The Japan Institute of Metals.