The Experimental Investigation Of Isothermal Section Of The Al-Cu-Mn System At 600℃ And 500℃

The isothermal section of the Al-Cu-Mn system at 600℃ and 500℃ were investigated over the whole composition range by means of X-ray diffraction (XRD), scanning electron microscopy equipped with energy dispersive X-ray analysis (SEM/EDS). The liquidus tempera(?) invariant reactions of some key alloys were determined by differential thermal analysis (DSC). Two new ternary compounds τ4 and τ5 were first discovered in this work. Single-phase alloy for τ4 was prepared successfully and its XRD pattern was obtained. τ4-Al61.8Cu34.4Mn3.8 has a Face-centered cubic crystal structure with space group Fm-3m (NO.225), the lattice constants a=5.8270393(A), and crystallizes with AlCu2Mn structure type. The XRD pattern for τ5-Al68Cu2oMn12 was obtained, but its crystal structure has not been determined. Four ternary compound τ1,τ2, τ3, and β which reported in literature were confirmed in this work and τ3 only observed in 500℃. And their homogeneity range at 600℃ and 500℃ were determinded in this work. Eight binary phases AlgMn5, (βMn), Al4Cu9, LT-Al11Mn4, R-Al4Mn, AlCu_θ, AlCu_η1(AlCu_η2) and AlCu_δ were observed to dissolve the third element. Beside, the solid (Cu) phase composition range was determined also.