Direct Rolling of TiCp/Ti-6Al-4V Composite for Improved Microstructure, Mechanical Properties, and High-Temperature Oxidation Resistance

Herein, the 5 vol% TiCp/Ti-6Al-4V composite is prepared by induction skull melting (ISM) and direct rolling in near-beta phase region. The microstructure, mechanical properties, and high-temperature oxidation behavior of the as-cast and as-rolled composites are systematically investigated. The investigations of microstructure reveal that the as-cast coarse alpha/beta lamellar matrix microstructure is translated to refined bimodal microstructure after direct rolling. And the coarse and segregated TiC particles tend to be refined and uniformly distributed in the matrix. Tensile test results exhibit that a well-matched strength and elongation is obtained after direct rolling. The tensile strength at room temperature (RT) and high temperature (650 degrees C) increases to 1291.9 and 472.5 MPa, respectively, while the as-rolled composite maintains a good elongation of 6.7% and 26.8%, respectively. The strengthening mechanism can be attributed to grain boundary strengthening and the load-bearing capability of TiC. Isothermal oxidation test indicates that as-rolled composite exhibits better oxidation resistance than as-cast composite both at 550 and 650 degrees C. The improved oxidation resistance is mainly a result of the significant refinement of oxides and consequently retarding the diffusion process.