Effect of cryogenic treatment on microstructure and mechanical properties of Cu<sub>40</sub>Zr<sub>44</sub>Ag<sub>8</sub>Al<sub>8</sub> bulk metallic glass composite

Abstract

The effect of cryogenic treatment on microstructure and mechanical properties of Cu₄₀Zr₄₄Ag₈Al₈ bulk metallic glass composite (BMGC) has been investigated. The microstructure and mechanical properties of BMGC before and after cryogenic treatment were characterized through optical micrograph (OM), X-ray diffraction (XRD), differential scanning calorimetry (DSC) and Vickers micro hardness (<italic>H</italic>_v). The results show that the formation of crystalline phase of Cu₄₀Zr₄₄Ag₈Al₈ BMGC can be obtained through the cryogenic treatment with 2 h. The dimension and volume fraction of crystalline phase increases with increasing of the cryogenic treatment duration from 2h to 24 h, which result in the improvement of micro hardness of BMGC. The Cu₁₀Zr₇ and AgZr phases were formed in Cu₄₀Zr₄₄Ag₈Al₈ BMGC after cryogenic treatment. The glass transition temperature of amorphous matrix of BMGC increases with the increase of cryogenic treatment duration. However, the crystallization exothermal heat of BMG decreases with the increasing of the cryogenic treatment duration. The internal stress induced by cryogenic treatment was associated with the microstructure evolution of Cu₄₀Zr₄₄Ag₈Al₈ BMGC.