Improving the glass-forming ability and plasticity of a TiCu-based bulk metallic glass composite by minor Ta doping

Abstract The effects of Ta doping on the glass-forming ability and the mechanical behavior of a B2 phase formable Ti-Cu-Ni-Zr bulk metallic glass composite have been investigated. The doped Ta causes the morphology change of in-situ precipitated B2 phase, from patch-like shapes to homogeneously distributed spherical shapes. The solid-dissolved Ta in the matrix improves the glass-forming ability, suppressing the precipitation of unexpected brittle Ti2Cu phase. Doping Ta with 2 at% generates a homogeneously distributed spherical B2 phase without other crystalline phases, and shows the best mechanical property, including a fracture strength of 1804 MPa and plastic strain of 3.2%. The precipitated B2 phase could hinder the rapid propagation of the main shear band, causing branching, stopping and multiplication of it. The multiplied shear bands accommodate the improved plasticity. The present study provides an important insight into tailoring the phase formation and plasticity of in-situ bulk metallic glass composites via minor alloying.