Microstructural heterogeneities governing the deformation of Cu47.5Zr47.5Al5 bulk metallic glass composites

Cu47.5Zr47.5Al5 rods with different volume fractions of crystalline B2 CuZr phase were prepared by copper mould casting. Based on microstructural investigations a solidification mechanism is proposed for these bulk metallic glass (BMG) composites. The composite microstructure enhances the compressive plasticity (plastic strain up to 14%) and both plastic strain as well as yield strength scale with the crystalline volume fraction. Yield strength and fracture strain were successfully calculated using a strength model, which considers percolation and an empirical three microstructural element body approach, respectively. Furthermore, B2 CuZr was synthesized by means of a thermal cycling treatment and uniaxial compression tests were carried out at room temperature. The intrinsic work-hardenability caused by a martensitic transformation has strong implications on the deformation behaviour of the investigated Cu47.5Zr47.5Al5 BMG composites.