Composition and orientation relationships of constituent particles in 3xxx aluminum alloys

Constituent and dispersoid phases in two Direct Chill-cast 3xxx aluminum alloys after low-temperature annealing, with different silicon content have been studied. The lattice parameters, chemical composition, morphology and orientations relationships of constituent particles with regard to Al matrix have been addressed. Al(Fe,Mn) is found to be the most prominent constituent phase in the alloy with a low Si content. The orientation relationship between aluminum matrix and this phase is determined as , , which is consistent with the orientation relationships of Al(Fe,Mn) dispersoids. –Al(Fe,Mn)Si constituent particles in the Si rich alloy have been found to have various possible orientations. A gradient of Fe content is found in the –Al(Fe,Mn)Si dispersoids due to slow diffusion of Fe into dispersoids during annealing.