An order of magnitude enhancement in ductility of a metallic glass of peak rejuvenation

Exceptional ductility has been a long-sought-after property of metallic glasses, and cryogenic thermal cycling rejuvenation has been actively explored to enhance the plasticity of metallic glasses. By tuning the holding time and number of cycles of cryogenic thermal cycling processing, we here report a (Zr0.8125Cu0.1875)79Ni10Al10Nb1 metallic glass of peak rejuvenation with the plasticity of an order of magnitude higher than that of the as-cast glass, without sacrificing its strength. Characterizations indicate that the loose atomic packing of the metallic glass of peak rejuvenation facilitates the generation and proliferation of shear bands in the early stage of plastic deformation, and the resultant dense shear bands tend to be deflected due to their interaction with each other and/or structural inhomogeneity in the matrix, hindering their rapid propagation and in turn increasing the plasticity. The combination of high relaxation enthalpy and high plasticity obtained here is outstanding from the previous rejuvenated metallic glasses which have either high relaxation enthalpy or high plasticity, while never both. This work identifies an alloy system with very high efficiency in plasticity improvement through cryogenic thermal cycling rejuvenation and represents a promising guide for improving the plasticity of metallic glasses.