Combined effect of isothermal annealing and pre-compression on mechanical properties of Cu36Zr48Al8Ag8 bulk metallic glass
(1. State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, China;
2. Faculty of Materials and Energy, Southwest University, Chongqing 400715, China)
2. Faculty of Materials and Energy, Southwest University, Chongqing 400715, China)
Abstract: The combined effects of isothermal annealing and pre-compression on the mechanical properties of Cu36Zr48Al8Ag8 bulk metallic glass (BMG) were investigated. The as-cast specimens were first annealed at 743 K for 10 min, and then pre-compressed under 800 MPa for 1, 3, 5 and 10 h, respectively. The results indicated that annealing resulted in the formation of nanocrystals with a diameter of ~10 nm in the amorphous matrix and a drastic decrease of the free volume, leading to complete loss of the plasticity of the BMG. Applying pre-compression under a stress of 800 MPa for a proper duration (5 h) resumed part of the lost free volume in the BMG matrix and therefore partially recovered the plasticity. A very long period of pre-compression (10 h) decreased the free volume again, which was caused by the excessive crystal growth.
Key words: bulk metallic glasses; annealing; pre-compression; free volume; nanocrystal