Mapping distributions of mechanical properties and formation ability on the ternary B―C―N phase diagram

Based on first-principles calculations, we present the distributions of mechanical properties and formation ability of amorphous BxCyNz solids on the ternary B–C–N phase diagram. Along the C–BN isoelectronic line, the formation energy shows symmetric distributions; the Young's modulus and ratio of bulk modulus and shear modulus (B/G) show zonal distributions. Amazingly, for some peculiar compositions (B: 13–17 at.%; C: 48–52 at.%; N: 33–35 at.%), B–C–N solids exhibit certain ductile characteristic that is comparable to metals. On the phase area (B: 15–30 at.%; C: 50–60 at.%; N: 20–30 at.%), B–C–N solids possess both excellent hardness and good formation ability. These theoretical results provide valuable guidance for intentionally synthesizing BxCyNz materials with desirable mechanical properties.

Research highlights
► B–C–N coatings as potential industrial applications.
► Relationship of mechanical property and composition has not been built.
► We studied the relationship.
► We evaluated the formation ability and mechanical property for different compositions.