Texture Evolution and Dynamic Recrystallization Behavior of Hybrid-Reinforced Titanium Matrix Composites: Enhanced Strength and Ductility

TiB, TiC and La2O3 hybrid-reinforced Ti-6Al-4V matrix composites were fabricated by common casting and processed by the following forging and isothermal extrusion. The texture evolution, dynamic recrystallization (DRX) behavior and mechanical properties of the as-extruded composites were investigated. The results show that DRXed regions and deformed regions formed during extrusion, strong 〈0001〉α, 101¯0α\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ \left\langle {10\bar{1}0} \right\rangle_{\alpha } $$\end{document} and weak 101¯1α\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ \left\langle { 1 0 {\bar{\text{1}}\text{1}}} \right\rangle_{\alpha } $$\end{document} fiber textures parallel to extrusion direction were formed due to the selection of slip system in α phase and inheritance from phase transformation according to Burgers orientation relationship. Additionally, the orientation of α grain in DRXed regions became randomized in comparison with the deformed regions. Micro-sized TiB short fibers not only acted as source to generated dislocations, but hindered dislocation slip to cause pile-ups around TiB, which is beneficial to stimulate dynamic recrystallization. Submicro-sized La2O3 particles distributed at the triple junction of grain boundaries could pin grain boundaries and hinder grain growth. Tensile test results show that the ultimate tensile strength got a 9.8 pct enhancement, from 834.3 ± 10 to 916.0 ± 10.6 MPa, accompanied by simultaneous improvement of elongation from 5.4 ± 0.6 to 12.2 ± 0.7 pct at room temperature. The simultaneous increase of strength and ductility was principally attributed to TiB fracture modes and grain refinement after extrusion.