Synthesis of Ferromagnetic τ-Mn–Al–C by Reactive Sintering

Abstract

Ferromagnetic Mn–Al–C (τ-phase) can be synthesized by a single-route conventional reactive sintering method. The maximum magnetization and coercivity were 75.8 Am²/kg and 57 mT, respectively. The τ-phase fraction was evaluated to be 81 mass% for Mn₅₅Al₄₅C₂ annealed at 1273 K. The τ-phase of Mn₅₅Al₄₅C₂ can be synthesized at an annealing temperature from 873 to 1273 K, whereas that of Mn₅₅Al₄₅ cannot be synthesized. It was indicated that the phase stability of the hcp-phase (ε-phase) was improved by adding carbon, resulting in an ε–τ transformation.

Fig. 4 T_a dependence of M_1.5T of Mn₅₅Al₄₅ and Mn₅₅Al₄₅C₂.