Dual Phase Synergy Enabled Large Elastic Strains of Nanoinclusions in a Dislocation Slip Matrix Composite.

Abstract

Freestanding nanomaterials (such as nanowires, nanoribbons, and nanotubes) are known to exhibit ultralarge elastic strains and ultrahigh strengths. However, harnessing their superior intrinsic mechanical properties in bulk composites has proven to be difficult. A recent breakthrough has overcome this difficulty by using a martensitic phase transforming matrix in which ultralarge elastic strains approaching the theoretical limit is achieved in Nb nanowires embedded in the matrix. This discovery, breaking a long-standing challenge, still limits our ability of harnessing the exceptional properties of nanomaterials and developing ultrahigh strength bulk materials to a narrow selection of phase transforming alloy matrices. In this study, we investigated the possibility to harness the intrinsic mechanical properties of nanoinclusions in conventional dislocation slip matrix based on a principle of synergy between the inclusion and the matrix. The small spacing between the densely populated hard and dislocation-impenetrable nanoinclusions departmentalize the plastic matrix into small domains to effectively impede dislocation motion within the matrix, inducing significant strengthening and large local elastic strains of the matrix, which in turn induced large elastic strains in the nanoinclusions. This dual phase synergy is verified in a Ti3Sn inclusions/B2-NiTi(Fe) plastic matrix model materials system. The maximum elastic strain of Ti3Sn inclusion obtained in the dislocation slip matrix is comparable to that achieved in a phase transforming matrix. This finding opens new opportunities for the development of high-strength nanocomposites.