Loss- free tensile ductility of dual- structure titanium composites via an interdiffusion and self- organization strategy

The deformation-coordination ability between ductile metal and brittle dispersive ceramic particles is poor, which means that an improvement in strength will inevitably sacrifice ductility in dispersion-strengthened metallic materials. Here, we present an inspired strategy for developing dual-structure based titanium matrix composites (TMCs) that achieve 12.0% elongation comparable to the matrix Ti6Al4V alloys and enhanced strength compared to homostructure composites. The proposed dual-structure comprises a primary structure, namely, a TiB whisker rich region engendered fine grain Ti6Al4V matrix with a three-dimensional micropellet architecture (3D- MPA), and an overall structure consisting of evenly distributed 3D- MPA reinforcements and a TiBw- lean titanium matrix. The dual structure presents a spatially heterogeneous grain distribution with 5.8 p.m fine grains and 42.3 p.m coarse grains, which exhibits excellent hetero- deformation-induced (HDI) hardening and achieves a 5.8% ductility. Interestingly, the 3D- MPA reinforcements show 11.1% isotropic deformability and 66% dislocation storage, which endows the TMCs with good strength and loss free ductility. Our enlightening method uses an interdiffusion and self-organization strategy based on powder metallurgy to enable metal matrix composites with the heterostructure of the matrix and the configuration of reinforcement to address the strength-ductility trade-off dilemma.

Automated summary

In this study, a new strategy for developing titanium matrix composites (TMCs) with a dual-structure is proposed. The TMCs achieve enhanced strength compared to homostructure composites, while maintaining 12.0% elongation comparable to the matrix Ti6Al4V alloys. This is achieved by using a TiB whisker rich region engendered fine grain Ti6Al4V matrix with a three-dimensional micropellet architecture (3D-MPA) as the primary structure and evenly distributed 3D-MPA reinforcements and a TiBw-lean titanium matrix as the overall structure.