Different magnetic field effects on the ϵ-τ Phase transformation between (mn,zn)-al and mn-al-c

In-magnetic-field annealing (IFA) effects on Zn-modified Mn-Al and Mn-Al-C were investigated at the annealing temperature of 573 K, which was around their $_Rftxt-{\mathrm {C}}$. Mn₅₃Zn₂Al₄₅ showed the magnetic-field-induced acceleration of the phase transformation to $\text{L}1-{0}$ -phase ( $\tau $ -phase) and the suppression of that to nonferromagnetic equilibrium phase. For Mn₅₅Al₄₅C₂, IFA effects were not clearly detected. These different magnetic field effects were discussed by the difference of the mechanism in stabilization of $\tau $ -phase. It is found by a thermal analysis that the modification of Zn stabilized $\tau $ -phase against $\epsilon $ -phase, realizing acceleration of transformation to $\tau $ -phase. The addition of carbon stabilized $\epsilon $ -phase against $\tau $ -phase. The ineffectiveness of in-field annealing for Mn-Al-C is due to the stabilization of $\epsilon $ -phase and the reduction of the Curie temperature. The combination of Zn modification and IFA is realized to synthesize high fraction of $\tau $ -phase for short annealing time and low annealing temperature.