The experimental investigation of phase equilibria in the Al-rich corner within the ternary Al–Mn–Be system

• We investigated the constitution of the Al-rich corner of the Al–Mn–Be system.
• Be4AlMn is a thermodynamically stable phase in the Al-corner of the Al–Mn–Be system.
• The T-phase (Al15Mn3Be2) is not a stable phase in the Al-corner at 600 °C.
• The λ-Al4Mn phase is a stable phase in the Al-corner at 600 °C.
• T-phase is a stable phase at 750 °C.

This work investigated the constitution of the Al-rich corner within the ternary Al–Mn–Be phase diagram using SEM + EDS, AES, XRD and DSC. With respect to the results, an isothermal cross-section at 600 °C was established, as well as a prediction of the apparent liquidus projection in the Al-corner. Be4AlMn is a thermodynamically stable phase in the Al-rich corner of the ternary phase diagram. The other ternary T-phase, usually designated as Al15Mn3Be2, formed during solidification in alloys with Be:Mn atomic ratios of less than 4:1, and having more than 1.5 at.% Mn. This phase is not a stable phase in the Al-rich corner at 600 °C. In contrast, the λ-Al4Mn phase is a stable one. The T-phase is stable over a rather large part of the phase diagram at least within a temperature range close to 750 °C, where it is in equilibrium with the Al-rich liquid phase, and Be4AlMn.