Microstructure evolution of bulk metallic glass during thermal oxidation under plastic strain

摘要

The microstructure evolution behavior of a Zr-based bulk metallic glass during thermal oxidation under plastic strain has been investigated. In the early stage of deformation, preexisting scale fractures in a brittle and intergranular way. Due to the concentrated strain field formed in front of crack tip, t - m martensitic transformation of t-ZrO2 takes place. With tensile strain increasing, multiple oxide regions consisting of t-ZrO2 dendrites form around fractures due to the combined action of oxidation, deformation and fracture. The formation and fracture of scales under large strains seriously deteriorate the surface finish and dimension accuracy of thermoplastic forming parts.