Effects of interface roughness on the annealing behaviour of laminated Ti-Al composite deformed by hot rolling

A laminated Ti-Al composite has been fabricated by hot compaction and hot rolling of alternate layers of commercial purity Ti and Al sheets with a thickness of 200 μm. The hot compaction temperature was 500 ̊C and in a following step the composite has been reduced 50% in thickness by hot rolling. The fully consolidated composite has been annealed at 300 ̊C and 500 ̊C for different length of time. As a result of the differences in crystal structure and mechanical properties between Ti and Al protrusions and retrusions formed at the interface. A heterogeneous interface has thereby been created. The heterogeneity affected the recovery kinetics of the aluminium phase which at 300 ̊C was faster near the interface than in the middle of the Al layer. This effect of a heterogeneous interface is of relevance when optimizing the thermomechanical processing of the composite to obtain high strength and formability for application.