The performance characteristics of alloy nitrides are mainly reflected in their physical, chemical, and functional properties, as follows:
Physical Properties
High Hardness and Wear Resistance: Alloy nitrides (such as ε-Fe₂₋₃N) have a hexagonal crystal structure, a density of approximately 5.8 g/cm³, and high hardness, making them suitable for wear-resistant material compositions.
Magnetic Properties: ε-Fe₂₋₃N exhibits ferromagnetism at room temperature with a high magnetic moment.
Thermal Stability: Alloy nitrides maintain structural stability at high temperatures, exhibiting good thermal stability.
Chemical Properties
Corrosion Resistance: Alloy nitrides (such as Fe₆N₂) are insoluble in water and resistant to acids, alkalis, and other chemicals, making them suitable for corrosive environments.
Oxidation Sensitivity: ε-Fe₂₋₃N is easily oxidized to nitrogen oxides in the presence of oxygen and requires sealed storage.
Functional Properties
Catalytic Activity: Nitride alloys exhibit excellent performance in Fischer-Tropsch synthesis, ammonia synthesis, and OER electrocatalysis. Nanoscale materials can also be used in magnetohydrodynamics and supercapacitors.
Permanent Magnet Potential: Iron-nitrogen permanent magnets (such as Fe₆N₂) are considered candidate materials to replace rare-earth permanent magnets due to their high magnetocrystalline anisotropy and low cost, but the coercivity and remanence balance issues need to be addressed.
Surface Engineering Applications: Nitriding treatments (such as gas nitriding) can improve the surface hardness (up to HV950-HV1200), wear resistance, and fatigue strength of steel parts, making them suitable for engine crankshafts, molds, etc.
Preparation and Structural Characteristics
Tunable Phase Structure: Nitride alloys contain multiple phases (such as Fe₂N, Fe₃N, Fe₄N, Fe₆N₂), and their performance can be optimized by controlling the preparation conditions. Interstitial alloy characteristics: The relatively wide interatomic spacing of iron atoms (0.28-0.30 nm) is conducive to the diffusion of nitrogen atoms.
