Synergistic improvement of strength and ductility is challenging in the engineering applications of titanium matrix composites (TMCs). Herein, we fabricated the TC4 composites reinforced with grain boundary micron-TiC and intragranular nano-Ti 2 Cu using spark plasma sintering (SPS) and hot rolling (HR) to achieve a good balance between strength and ductility. An interfacial reaction between Ti and C forms the grain boundary TiC, and the vast majority of intragranular nano-Ti 2 Cu precipitates to accommodate the severe lattice distortion caused by the solid solution of Cu in β-Ti phase. Benefiting from Ti 2 Cu nanoprecipitates and their ability to effectively suppress dislocation motion , precipitation strengthening, and dislocation strengthening are the main factors, in addition to grain refinement strengthening due to deformation processing , that contribute to the realization of the superior yield strength (YS) of 1360 MPa and ultimate tensile strength (UTS) of 1504 MPa in composites than TC4 matrix (YS = 986 MPa, UTS = 1160 MPa). Meanwhile, the interfacial strain-delocalization effect of TiC/Ti 2 Cu with Ti matrix, the shear-lag effect of TiC, and the sustained strain-hardening effect provided by TiC/Ti 2 Cu empower the composites with an outstanding ductility (fracture elongation of 8.4 %). This study highlights the untapped potential for improving the mechanical properties of Ti matrix composites.
In this study, low energy ball milling and spark plasma sintering techniques prepared the in-situ synthesized Ti 5 Si 3 reinforced Ti-6Al-4V (TC4) matrix composites and then rolled them at high temperatures. In the composites with high Si content, the Ti 5 Si 3 particles distributed at the interface of α-phase and β-phase agglomerated and then formed a quasi-continuous network structure, which will deteriorate the plasticity of the composites. After hot rolling, the grains of the composite were significantly refined, and more Ti 5 Si 3 particles were precipitated. With the increase in Si content, the tensile strength of sintered composites increased slightly, but the elongation decreased greatly. After hot rolling, the tensile strength of the composite increased significantly with an increment of 359.4 MPa, among which the composite with 0.6 wt% Si achieved a synchronous increase in strength and plasticity. The strengthening mechanism of sintered composites included dislocation strengthening, solution strengthening, and grain refinement, among which dislocation strengthening and grain refinement were the main strengthening mechanisms. The strengthening mechanism of rolled composites was mainly the dislocation strengthening caused by rolling, the grain refinement, and the mismatch of thermal expansion coefficient.
危险品化学品经营许可证（带存储）