Internal stresses induced by plastic shear deformation of Zr–(Cu,Ag)–Al bulk metallic glasses

Effective internal shear stress σi induced by torsional deformation of Zr46(Cu4/5Ag1/5)46Al8 and Zr46Cu46Al8 bulk metallic glasses different by the glass-forming ability of the maternal melts has been determined by measurements of stress relaxation upon stepwise unloading. It has been found that the ratio σi/σ0 (σ0 is the initially applied shear stress) decreases upon increasing the temperature from ≈ 0.8 at T = 450K (T ≈ 0.64 × Tg) to ≈ 0.08 at T = 638K (T ≈ 0.91 × Tg) independently of σ0 and glass composition. The obtained result is in good agreement with earlier data obtained on ribbon metallic glasses. The origin of deformation-induced internal stresses and their connection with deformation mechanisms of metallic glasses has been briefly discussed.