Study On The Properties Of Some Chemical Measures Of M - C Compounds In High Speed ​​Steel

High speed steel, namely tool steel have attracted extensively study owing to its outstanding properties such as high hardness, super wear resistance, high heat resistance, good processing properties, excellent strength and good ductility. This work mainly focuses on the calculations and studies the MC (M=Ti, V, Zr, Nb, Hf, Ta), M3C (M=Cr, Mn, Fe, Co, Ni), M2C(M=Mo, W) and M23C6(M=Cr, Mn, Fe, Mo, W) phase of high speed steel by means of first-principles calculations together with semi-experiential Debye’s quasi-harmonic approximation theory. The structural properties of these compounds are obtained. The basic mechanical properties and electronic properties can be obtained after build the crystal structure of these compounds using first-principles calculations.The cohesive energy and formation enthalpy of MC, M2C, M3C and M23C6compounds are estimated. The results indicate that all of compounds are thermodynamic stability, which illustrate these compounds may be obtained easily in experiment. Moreover, our results are good agreement with the experimental data.The mechanical properties of MC, M2C, M3C and M23C6compounds are illustrated. The elastic constants of these compounds are calculated using stress-strain. The moduli of these compounds can be estimated using Voigt-Reuss-Hill approximation methods from the known elastic constants, which include bulk modulus (B), shear modulus (G), Young’s modulus (E) and Poisson’s ratio (σ). The bulk modulus, shear modulus and Poisson’s ratio of MC compounds are217.5-294.0GPa,150.3-205.7GPa and0.173-0.239, respectively. The hardness of MC compounds is less than30GPa. The bulk modulus, shear modulus and Poisson’s ratio of M2C compounds are289.3-336.8GPa,149.1-190.6GPa and0.26-0.29, respectively. The bulk modulus and shear modulus of M3C are199.0-320.2GPa and71.0-150.6GPa, respectively. According to the ratio of bulk modulus to shear modulus known that these M3C compounds are more ductility. The bulk modulus and shear modulus of M23C6are301.0-339.6GPa and126.9-163.7GPa. Also, the moduli of these compounds doped with chromium, molybdenum and tungsten are larger than these compounds without doped with these atoms. In addition, the mechanical anisotropy and anisotropic sound velocity of M3C and M2C compounds are discussed. The results show that the anisotropic properties of Young’s modulus are stronger than the bulk modulus. The mechanical anisotropy of M23C6compounds is also estimated. The results illustrate that the anisotropic properties of Young’s modulus for Fe23C6are stronger than other carbides among M23C6compounds. The electronic properties of MC, M3C and M23C6compounds are discussed by means of density of states and Mulliken population analysis. The results indicate that the bonding in these compounds can be classified as a combination of metallic and covalent characters.