Characterization of Ni-based metallic glass in a crystalline-amorphous composite synthesized by accumulative roll bonding

Abstract

Bulk Metallic Glasses (BMGs) are known for their ultra-high strength but little or no plasticity. Synthesizing crystalline-amorphous (C-A) composites presents a way by which the plasticity can be improved. In the present study, Accumulative Roll Bonding (ARB) is used to process a composite of copper/nickel and a nickel-based metallic glass up to four cycles. Current research aimed to characterize the amorphous phase. Using optical microscopy, rupture of the MG was detected after one cycle. The C-A sheets deformed inhomogeneously, leading to multiple fractures of the MG layers. Further ARB passes showed that the MG fragments were broken into smaller pieces and distributed more homogeneously in the matrix. Nanoindentation studies revealed an increase of 11.34% in the hardness of the MG after the fourth ARB cycle and a 16.06% increase in the hardness of the MG due to annealing. The same trend was observed with the elastic modulus of the MG