Tunable the mechanical properties of β-Ti 1-x M x binary alloys by transition metal M (M = Fe, Mo, Nb, Ni) substitutional doping: A first-principles study

The structural stability, electronic, and mechanical properties of Ti 1-x M x (M = Fe, Mo, Nb, Ni) binary alloys were systematically investigated through first -principles calculations based on Density Functional Theory (DFT). The results indicate that the formation energy decreased with an increase in the substitutional atomic M content, accompanied by an increase in the values of C 11 - C 12 . This observation suggests a significant improvement in the structural stability of the Ti 1-x M x alloys considered, with the concentration of substitutional atomic M ranging from 6.25 % to 50 %. Furthermore, the mechanical parameters, including bulk modulus B and shear modulus G, exhibited a linear increase with the concentration of the alloy element M. The Young ' s modulus E of Ti 1-x Fe x and Ti 1-x Nb x alloys increased, whereas Ti 1-x Mo x and Ti 1-x Nb x alloys reached a minimum value. In addition, the B / G ratio and Poisson ' s ratio nu indicated that beta -Ti 1-x M x alloys are fundamentally ductile materials. Moreover, using the stretching model, we demonstrate that the tensile strength of Ti 1-x M x alloys was significantly improved by increasing the alloy element M concentration. The enhancement in tensile strength was primarily attributed to the enhanced bond strength between Ti and M atoms, as revealed by the analysis of the density state. These findings provide a pragmatic approach for reinforcing the strength -toughness compatibility of Ti -based alloys, rendering them suitable for aerospace industry applications.