Coherent interface driven super-plastic elongation of brittle intermetallic nano-fibers at room temperature

Abstract

The intermetallic compound such as Ni 2 Si has a brittle nature. Therefore, monolithic intermetallic compounds have not yet been prepared by mechanical downsizing. During mechanical drawing of bulk CuNi 2 Si alloy at room temperature, we observed more than 400% plastic elongation of hard and brittle Ni 2 Si intermetallic nano-fibers. The calculation based on the density functional theory reveals that the fully coherent interface induces strain on the intermetallic compound surrounded by the matrix, and lowers the intrinsic stacking fault energy below the level required to break an interatomic bond. The new interface between the Ni 2 Si intermetallic and Cu matrix formed by the plastic deformation is as stable as the original coherent interface formed by precipitation, and the activation energy of the newly formed interface to slip is similar to that of the Cu matrix. All of these make plastic deformation of brittle Ni 2 Si intermetallic possible by slip without failure. (c) 2022 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.