Kinetic study of embrittlement of Ti- and Zr-based metallic glasses caused by annealing-induced structural relaxation

We have clarified relation between embrittlement behavior and crystallization or structural relaxation behavior of Zr₅₅Cu₃₀Al₁₀Ni₅ and Ti_47.4Cu₄₂Zr_5.3TM_5.3(TM = Ni, Co, Fe) metallic glasses. The embrittled samples were prepared by isothermal annealing at various temperatures and times. The embrittlement behavior of the metallic glasses was compared with the crystallization and structural relaxation behavior estimated by kinetic calculation. In the present study, we have clarified as follows, (1) The Zr₅₅Cu₃₀Al₁₀Ni₅ metallic glass becomes brittle with precipitation of crystal, and the behavior agrees with the kinetic calculation of crystallization. (2) The Ti_47.4Cu₄₂Zr_5.3Ni_5.3 metallic glass is embrittled with structural relaxation, and the behavior agrees with the kinetic calculation using DSC-heat flow of glass transition. (3) The Ti_47.4Cu₄₂Zr_5.3TM_5.3(TM = Co, Fe) metallic glasses are also embrittled with structural relaxation, although embrittlement behavior of these glasses is influenced more sensitively by the structural relaxation compared with the Ti_47.4Cu₄₂Zr_5.3Ni_5.3metallic glass.