Al-Mn-Zn ternary system is experimentally investigated at 400℃ via diffusion couples and key samples experiments. Three new ternary compounds have been found in the current study. Phase relations and homogeneity ranges are determined for binary and ternary phases through EPMA, SEM/EDS and XRD. Compositions of the ternary intermetallic compounds τ1, τ2 and τ3 have been found as Al62Mn16Zn22,Al76Mn13Zn11  and AlxMnyZnz (x=9.5-12.7 at%; y=11-15 at%; z=74.6-77.2 at%). Al4Mn is found to form quasicrystal or stable equilibrium phase in the presence of Zn and depending on the solidification conditions. Binary compounds Al4Mn, Al11Mn4, Al8Mn5 and β-Mn exhibit limited ternary solid solubility. Experimental data on this system from the literature is spare, isothermal section of the Al-Mn-Zn phase diagram at 400℃ is constructed based on the current phase analysis results and experimental data.
DSC analysis approach is also used to investigate this ternary system. Partial vertical sections at 13, 14 and 15 at% Mn have been experimentally investigated and compared with preliminary thermodynamic calculations. Discrepancy is observed due to the absence of the ternary phases in the thermodynamic database. Thus, this ternary system has to be remodeled in the future.