A first principles study of the effect of Mo on Cr-containing carbides in carbidic austempered ductile iron

Abstract

In this paper, the effects of Mo doping content on the structural stability, mechanical and electronic properties of Cr-containing carbides (Fe₃Cr₄C₃) are investigated by means of first-principle calculations. The results show due to the difference in atomic radius between Mo and Cr atoms, Mo doping will increase the crystal volume of the carbide, and at the same time, it will lead to lattice distortion leading to lattice mismatch, with the increase of Mo content will make the symmetry decrease, and the carbide tends to be transformed from hexagonal to monoclinic crystal system, and the doping of Mo atoms will also make the stability of the carbide decrease, leading to the decrease in the overall stiffness and strength, and become softer. Wyckoff's Fe₃Cr₂Mo₂C₃ carbides with 2b (Mo)6c (Fe) 2c (Mo)4c (Cr) sites achieve higher Young's modulus with higher B/G and Poisson's ratio. (Fe, Cr, Mo)₇C₃ is anticipated to be a material with both high strength and high toughness.