Dual Acceleration of ε-τ Transformation in Mn–Al Induced by Zn-Addition and In-Magnetic-Field Annealing

抄録

Combined accelerating effects of ε–τ phase transformation by in-magnetic-field annealing and Zn-addition were investigated for Mn₅₃Zn₂Al₄₅ in magnetic fields up to 15 T. The in-field annealing for Zn-added sample accelerated the ε–τ transformation 16 times faster than Mn₅₅Al₄₅ at annealing temperature of 623 K. The reduction of magnetization after finishing ε–τ transformation was also more rapid than that of Mn₅₅Al₄₅. However, magnetic-field-induced acceleration of ε–τ phase transformation and suppression of precipitation of β-phase were observed for Zn-added alloy Mn₅₃Zn₂Al₄₅ annealed at 573 K. The obtained results suggested that the β-phase stabilized against both τ- and ε-phases by Zn-addition. Therefore, although the ε–τ transformation was efficiently accelerated by in-field annealing of Mn₅₃Zn₂Al₄₅, more precisely control of annealing time is required for obtaining high fraction of ferromagnetic τ-phase.

Fig. 6 Annealing time t dependence of M_1.5T of ZFA and IFA for Mn₅₃Zn₂Al₄₅ at 573 K (a) and 623 K (b). The inset shows t dependence of M_1.5T of ZFA and 15T-IFA for Mn₅₅Al₄₅ at 623 K.¹⁶⁾