Microstructure and mechanical properties of Ti-Ta based composites enhanced by in-situ formation of TiC particles

Abstract

TiC particle reinforced titanium matrix composites show excellent mechanical properties, which are widely regarded as promising high-performance structural materials. Here, we fabricated in-situ TiC enhanced Ti Ta based composites through mechanical alloying of elemental Ti and Ta powders and subsequently followed by spark plasma sintering and hot rolling. The stearic acid was utilized as both process control agent and carbon source. Experimental results show that Ti-enriched area, Ta-enriched area and TiC particles can be observed after sintering, and TiC particles are all distributed inside Ti-enriched area. After hot rolling, Ti-enriched areas and Ta-enriched areas are elongated along the rolling direction. The tensile strength increases and the ductility decreases with increasing content of in-situ formed TiC particles. The yield strength, the ultimate tensile strength of Ti Ta composite with 8 wt% TiC reach up to 1035 MPa and 1287 MPa, respectively, with a ductility of 1.6%. The enhanced strength is due to dislocation hardening, solid solution between Ti and Ta, grain boundary hardening and TiC particulate reinforcement. Besides, the solid solution of O element and the heterogeneous structure of Ti Ta composites may also improve the strength. This method provides an efficient way to fabricate in-situ TiC particle enhanced titanium based composite with improved strength. • The Ti-Ta composites presented heterogeneous structure with Ti-enriched, Ta-enriched and diffusional regions. • TiC particles were generated through in-situ reaction between Ti matrix and stearic acid. • The strength enhanced by in-situ formed TiC particles is higher than 200 MPa. • The strengthen mechanisms were determined to simulate the strength of Ti-Ta composites.