Mechanochemical nitridation by ball milling iron with m-phenylene diamine

• Published in: Journal of magnetism and magnetic materials 2003-02, Vol.257 (1), p.95-99
• Main Authors: Zhuge, L.J., Yao, W.G., Wu, X.M.
• Format: Article
• Language: English
• Subjects: Ball milling; Cold working, work hardening; annealing, post-deformation annealing, quenching, tempering recovery, and crystallization; Cold working, work hardening; annealing, quenching, tempering, recovery, and recrystallization; textures; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Cross-disciplinary physics: materials science; rheology; Domain effects, magnetization curves, and hysteresis; Exact sciences and technology; Fe and its alloys; Iron nitride; Machining, milling; Magnetic properties; Magnetic properties and materials; Magnetization curves, hysteresis, Barkhausen and related effects; Magnetization curves, magnetization reversal, hysteresis, barkhausen and related effects; Materials science; Materials synthesis; materials processing; Nitridation; Physics; Studies of specific magnetic materials; Thermal stability; Treatment of materials and its effects on microstructure and properties
• ISSN: 0304-8853
• DOI: 10.1016/S0304-8853(02)01054-5

The solid state synthesis reactions between elemental α-Fe powder and m-phenylene diamine (C 6H 4(NH 2) 2) have been studied. The different phase transformations are found in the course of milling and during subsequent thermal annealing. The single ε-Fe 2–3N phase with nitrogen concentration up to 11.53 wt% was obtained after 250 h ball milling. Owing to the local inhomogeneity of N content, the ε-Fe 2–3N phase can be formed by ball milling at room temperature, even though the sample has a low average N content. The saturation magnetization M S and coercivity H C of ε-Fe 2–3N are 81.4 A m 2/kg and 16.28 kA/m. Thermal analysis experiments show structural stability of the ε-Fe 2–3N phase up to 512.0°C. On comparison with α-Fe ball milled in NH 3 atmosphere, it is evident that the nitridation process in our experiment occurs more rapidly because more active nitrogen-containing radicals can be maintained during the milling process. It illustrates that the solid–solid reaction is more efficient than the solid–gas reaction.