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 TiSn inclusions/B2-NiTi(Fe) plastic matrix model materials system. The maximum elastic strain of TiSn 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.

A eutectic dual-phase design towards superior mechanical properties of heusler-type ferromagnetic shape memory alloys

“…The toughening strategy for Heusler alloys is to hinder crack propagation in the brittle Heusler phase by the introduction of the ductile γ phase. The optimisation of this strategy can be achieved by maximising the departmentalisation of the brittle Heusler matrix using γ phase with suitable grain size, and such strategy is analogous to the departmentalisation of a dislocation slip matrix for achieving high toughness and large strains of nanoinclusions in a NiTi/Ti3Sn system [61]. For a dual-phase structure, four possible configurations may be envisaged based on the dimension and interspacing of the γ phase, which are schematically shown in Figure 11.…”

Endowing low fatigue for elastocaloric effect by refined hierarchical microcomposite in additive manufactured NiTiCuCo alloy

“…In the NiTi-based composites that matrix is lattice-shear deformed by transformation, the load-bearing phase not only brings in strong back stress field at the interface to resist dislocation movement [47,57], but also exerts elastic interaction with matrix that may promote the martensitic transformation [10,43]. Furthermore, as the phase sizes are reduced and interfacial densities are boosted, the elastic coupling between the phases would be improved significantly, acquiring a synergistic enhancement on elastocaloric effect.…”

In Situ Synchrotron X-ray Diffraction Investigations of the Nonlinear Deformation Behavior of a Low Modulus β-Type Ti36Nb5Zr Alloy

“…Considering that the present alloy exhibits a strong <110> fiber texture (i.e., (110) β perpendicular to the LD), it is proposed that the recoverable strain of the present Ti36Nb5Zr alloy is mainly contributed by the elastic strain of the β phase. It has been reported that the martensitic transforming alloy can exhibit much larger elastic strain than the conventional dislocation slip alloy [52]. The possibility of SIMT implies the structural instability of the parent phase, and the uniform lattice distortion provided by martensitic transformation can suppress strain localization and damage accumulation [53].…”