Analysis of intermetallic phases in wrought aluminium alloy prepared by recycling of composite scrap

The intermetallic phases are analysed in recycled aluminium alloy with chem ical composition Al-2.2Cu-1.7Mg-1.1Ni-0.2Cr-1.1Fe-0.2Mn-0.9Si-0.2Ti-0.3Zn ( wt. %) and its mechanical properties are compared to those of industrially produced aluminium alloys with similar chemical composition. The structure of the alloy is composed of aluminium based (cu-Al) dendrites and multiphas e interdendritic region. During heat treatments the nucleation and growth o f fine precipitates of Mg2Si, Al2Cu, and Al2CuMg intermetallic phases are o bserved in the a-Al solid solution. The interdendritic region contains seve ral intermetallic phases with different size and morphology. The major inte l:metallic compound identified in this region is Al9Fe(Ni,Si) and minor pha ses are Mg2Si, Al4Cu2Mg8Si7, Al4CuMg5Si4, AlCuMg, (Cu,Al)(2)Mg, Al7Cu4Ni, A l-Cu-Ni, and Al-5(Fe,Cr)Si. After heat treatments the ultimate tensile stre ngth varied between 396 and 421 MPa, 0.2% yield strength between 305 and 37 2 MPa, and elongation between 8 and 19%. The ductility of the alloy decreas ed with increasing annealing time and temperature.