Ab initio study of the alloying effect of transition metals on structure, stability and ductility of CrN

TL;DR

This study uses first-principles calculations to explore how alloying transition metals affect the structure, stability, and ductility of CrN, revealing specific tendencies for phase separation and ductility enhancement.

Contribution

It provides detailed insights into the alloying effects on CrN's properties, highlighting the stability and ductility changes due to various transition metal additions.

Findings

Cr1-xYxN tends to phase separate due to high mixing enthalpy.

Cr1-xTaxN remains stable across compositions with negative mixing enthalpy.

Adding V, Nb, Ta, Mo, or W increases CrN's ductility.

Abstract

The alloying effect on the lattice parameters, isostructural mixing enthalpies and ductility of the ternary nitride systems Cr1-xTMxN (TM=Sc, Y; Ti, Zr, Hf; V, Nb, Ta; Mo, W) in the cubic B1 structure has been investigated using first-principles calculations. Maximum mixing enthalpy due to large lattice mismatch in Cr1-xYxN solid solution shows a strong preference for phase separation, while Cr1-xTaxN exhibits a negative mixing enthalpy in the whole compositional range with respect to cubic B1 structured CrN and TaN, thus being unlikely to decompose spinodally. The near-to-zero mixing enthalpies of Cr1-xScxN and Cr1-xVxN are ascribed to the mutually counteracted electronic and lattice mismatch effects. Additions of small amounts of V, Nb, Ta, Mo or W into CrN coatings increase its ductility.