Designing ductile CuZr-based metallic glass matrix composites

The CuZr-based metallic glass matrix composites (MGMCs) with different volume fractions of crystalline phases were designed by doping of nickel. Minor addition of nickel element can change the glass-forming ability of the resultant composites. Large compressive plasticity accompanied by strong work-hardening capacity was achieved in the Cu47Zr48Al4Ni1 composite with a volume fraction of crystalline phases of 33%. The excellent compressive properties were mainly attributed to the inhibition for the propagation of shear bands by the ductile crystals and deformation induced martensitic transformation of the B2-CuZr phase. However, no obvious global tensile ductility was obtained, due to the mode I fracture toughness and small plastic-zone size of glass matrix. To uncover the shear-band evolution during deformation, finite element simulation was conducted, revealing that the ductile B2 phase can tune the shear-stress distribution and consequently initiate and retard shear bands, which stimulates the multiplication of shear bands. Accordingly, the spacing of B2 CuZr particles is a vital factor dominating the plasticity of CuZr-based MGMCs, especially upon tension.