Effects of the microstructure and mechanical properties of Cr 3 C 2 powders added to Ti-25Nb-25Mo-15Ni medium entropy alloys

Abstract

This study fabricated Ti-25Nb-25Mo-15Ni-xCr₃C₂ composites and added differing proportions of Cr₃C₂ powder (where x represents 1, 3, and 5 mass%, respectively) using the vacuum sintering process-a powder metallurgy technique. The composites were simultaneously vacuum sintered at 1150, 1175, 1200, and 1225°C for 1 h, respectively. The experimental results indicate that the specimens exhibited optimal properties when the Ti-25Nb-25Mo-15Ni-1Cr₃C₂ composites were sintered at 1225°C for 1 h. The sintered density increased to 7.29 ± 0.15 g·cm⁻³, while the TRS improved to 684.23 ± 24.65 MPa, the flexural modulus increased to 69.64 ± 0.21 GPa, and the hardness rose to 75.88 ± 1.19 HRA. The EBSD and TEM results show that niobium, molybdenum, and chromium can form a strong solid solution with titanium, contributing to the solid solution strengthening effect. Moreover, nickel forms TiNi and Ti₂Ni intermetallic compounds with titanium, which are dispersed in the titanium matrix and effectively enhance its mechanical properties.