Experimental investigation on the phase equilibria of the Mn–Ni–Zn system at 400 °C

Partial isothermal section of the Mn–Ni–Zn system at 400 °C was experimentally established by means of XRD and SEM/EDS techniques. Three ternary compounds, i.e. T, τ1 and τ2, were found to exist at 400 °C for the first time. The compound T having an approximate formula of Mn7Ni7Zn86 was indexed as fcc structure with a lattice parameter of a = 1.81476 (1) nm. τ1, the structure of which is unknown, has an approximately stoichiometric composition of about 29 at.% Mn, 38 at.% Ni and balanced Zn. τ2 has fcc structure and a composition range of about 46–40 at.% Mn and constant 30 at.% Zn. Extended single-phase regions of the phases Mn5Zn21, Ni2Zn11, NiZn3, NiZn and β-Mn were observed. The maximum solubility of Ni in Mn5Zn21 and those of Mn in Ni2Zn11, NiZn3 and NiZn were determined to be 10, 6, 26 and 25 at.% at 400 °C, respectively.