A First-Principles Study of Mechanical and Electronic Properties of Cr0.5-xAl0.5TMxN Hard Coatings (TM = Ti, V, Y, Zr, Hf, and Ta)

Abstract

The structural, mechanical, and electronic properties of cubic Cr0.5-xAl0.5TMxN, doped with TM (transition metal) elements (TM = Ti, V, Y, Zr, Hf, and Ta) at low concentrations (x = 0.03 and 0.06), was investigated by first-principles calculations. The results of the structural properties calculations reveal that the addition of Ti, Y, Hf, Zr, and Ta expand the volume, while V has the opposite effect. All doped compounds are thermodynamically stable, and Cr0.5-xAl0.5TMxN with TM = Ti is energetically more favorable than other doped compounds. At the same doping concentration, Cr0.5-xAl0.5VxN possesses the highest stiffness, hardness, and resistance to external forces due to its greatest mechanical properties, and Cr0.5-xAl0.5TaxN possesses the highest elastic anisotropy and the lowest Young’s modulus. Substituting Cr atoms with TM atoms in a stepwise manner results in a decrease in the bulk modulus, shear modulus, Young’s modulus, and theoretical hardness of Cr0.5-xAl0.5TMxN, while increasing its toughness. Based on the calculation results of the total and partial density of states of Cr0.5Al0.5N and Cr0.47Al0.5TM0.03N, all compounds exhibit metallic behavior as indicated by the finite density of states at the Fermi level. The contribution of Ti-3d, V-3d, and Ta-3d orbitals at Fermi level is significantly higher than that of other TM atoms, resulting in a more pronounced metallic character for Cr0.47Al0.5Ti0.03N, Cr0.47Al0.5V0.03N, and Cr0.47Al0.5Ta0.03N.

First-Principles Calculations of the Mechanical Properties of Doped Cu3P Alloys

“…The influence of various microalloying elements on the mechanical properties of copper-phosphorus brazing materials is still the research focus in this field. However, due to the long cycle time and low efficiency of traditional experiments, computational materials science has become an emerging discipline covering computer and materials science [11,12], which simplifies the research process by calculating the doping of Cu-P brazing materials through the first nature principle, which can screen out the elements that satisfy the properties for experimental verification [13]. In this paper, we choose to add the elements of group 3A (Al and In), group 4A (Si, Ge, Sn, and Pb), group 5A (Sb and Bi), group 3B (Sc and Y), group 4B (Ti, Zr, and Hf), and group 5B (V, Nb, and Ta) into the Cu 3 P phase, in which many compounds of As contain toxicity, and therefore are excluded in this paper.…”