Influence of combinatorial annealing and plastic deformation treatments on the intrinsic properties of Cu46Zr46Al8 bulk metallic glass

Abstract In this paper, the effect of severe plastic deformation (SPD) induced by high-pressure torsion (HPT) and isothermal heat treatment (HT) below the glass transition on the structure-property relationships of Cu46Zr46Al8 bulk metallic glass (BMG) is assessed separately and alternately in reference to the as-cast state. Pronounced modifications are confirmed by X-ray diffraction, differential scanning calorimetry, dynamic mechanical analysis (DMA), dilatometry analysis, and scanning electron microscopy. Diffusion-controlled crystallization is achieved via HT with optimized parameters, and HPT is used afterwards to disperse crystalline phases relatively homogenous throughout the matrix. The dispersion of the second phase improves the thermomechanical stability around the glass transition temperature, as confirmed by DMA. Compared to a single HT process, a sequential combination of HT + HPT leads to a glass showing a linear hardness profile with values higher than the as-cast state. This study provides insights into possible processing routes for enhancing the mechanical and/or thermal properties of CuZr-based BMGs, which can also be used to tailor new design routes for other BMG systems.