Stress-induced structural change during superplastic deformation of bulk Zr-based metallic glass

The stress distribution of Zr41.2Ti13.8Cu12.5Ni10Be22.5 metallic glass subjected to uniaxial compression in the supercooled liquid region was examined. The FEM results indicate a triaxial compressive stress at the top surface and core regions, and a compress-tensile stress at the circumferential region. Microhardness and thermal properties of the three regions were analyzed. It was found that the circumferential region had less crystallization and smaller hardness value. In order to vary the stress state, a constraining aluminum ring was also applied to the BMG specimen for a compression test. The findings show that the crystallization behavior and stress states of the BMG with the aluminum ring are different from that without the ring. The stress-induced structural change of the BMG is analyzed in the paper in terms of the spheric stress and the effective strain.