Experimental Investigation of the Phase Equilibria in the Al-Mn-Zn System at 400°C

摘要

Al-Mn-Zn ternary system is experimentally investigated at 400°C using diffusion couples and key alloys. Phase relationships and homogeneity ranges are determined for binary and ternary compounds using EPMA, SEM/EDS, and XRD. Reported ternary compound T3 (Al11Mn3Zn2) is confirmed in this study and is denoted asτ2in this paper. Two new ternary compounds (τ1andτ3) are observed in this system at 400°C.τ1is determined as a stoichiometric compound with the composition of Al31Mn8Zn11.τ3has been found to have homogeneity range of AlxMnyZnz(x=9–13 at%;y=11–15 at%;z=75–77 at%). The binary compounds Al4Mn and Al11Mn4exhibit limited solid solubility of around 6 at% and 4 at% Zn, respectively. Terminal solid solution Al8Mn5is found to have maximum ternary solubility of about 10 at% Zn. In addition, ternary solubility of Al-richβ-Mn′ at 400°C is determined as 4 at% Zn. Zn-richβ-Mn′′ has a ternary solubility of 3 at% Al. The solubility of Al in Mn5Zn21is measured as 5 at%. Based on the current experimental results, the isothermal section of Al-Mn-Zn ternary system at 400°C has been constructed.