Insights to the fracture toughness, damage tolerance, electronic structure, and magnetic properties of carbides M2C (M = Fe, Cr)

The fracture toughness, damage tolerance, electronic structure, and magnetic properties of M2C (M = Fe, Cr) carbides were analyzed using first-principles calculations. Calculations of formation energy and modulus of elasticity indicate that a Cr/Fe ratio of 1/3 is a critical threshold which triggers a significant increase in the corresponding stability and related mechanical properties. Cr atomic content enhances the crack resistance, while Cr has a significantly detrimental effect on damage resistance. The electronic properties demonstrated that the Cr atom content enhances the metallic, ionic and covalent bonding. Furthermore, the reduction in the coordination number of Fe atoms is the main reason for the reduction in the local magnetic moment of the low-spin Cr atoms, which is strongly supported by the electronic structure. These studies provide detailed insights into Cr-containing carbides, providing valuable theoretical and technological information for the knowledge-based design and prediction of the mechanical properties of chromium-containing iron-based materials.