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

Abstract Effective internal shear stress σ i induced by torsional deformation of Zr 46 (Cu 4/5 Ag 1/5 ) 46 Al 8 and Zr 46 Cu 46 Al 8 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 σ i / σ 0 ( σ 0 is the initially applied shear stress) decreases upon increasing the temperature from ≈ 0.8 at T = 450K ( T ≈ 0.64 × T g ) to ≈ 0.08 at T = 638K ( T ≈ 0.91 × T g ) independently of σ 0 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.