Designing TiC@GNPs reinforced pure Ti matrix composites by mechanochemical ball milling and semi-solid sintering

Abstract

Zai-Yu Zhang, Jian-jun Yang, Yuan Yang, Liang Cao, Zai-Qi Zhang

In this work, we report on a novel in-situ TiC nanoparticles sticking to graphene nanoplatelets (TiC@GNPs) reinforced titanium matrix composites. In-situ TiC nanoparticles are produced in both mechanical ball milling and sintering processes. Ultrafine composite powder is obtained by mechanochemical ball milling from refined pure titanium powder and graphene nanoplatelets (GNPs) .A new type of TiC@GNPs/Ti composite materials with high strength and toughness and three-dimensional network distribution are made of ultrafine composite powder by various curing methods. The effects of different hot pressing parameters and reinforcing phase content on the microstructure and mechanical properties of the composites were studied. The results shown that the strength and plasticity of the ultrafine TiC@GNPs/Ti composites prepared by hot pressing sintering are obviously improved compared with the matrix. The strengthening mechanism of composites is mainly the synergistic effect of fine grain strengthening and dislocation strengthening. The ductility is due to grain refinement and in situ layered structure of TiC@GNPs particles. This layered structure is a double-scale microstructure, which is characterized by the lamellar composed of ultrafine bcc-Ti and ultrafine GNPs surrounding the fine crystal equiaxed fcc second phase TiC. The in-situ synthesis of nano-tic and nano-GNPs synergistic growth shows a criss-cross in the microstructure. The three-dimensional network distribution of GNP in titanium matrix can regulate the contradiction between strength and plasticity of titanium matrix composites.

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