Microstructure and mechanical properties of Al/Ti/Al laminated composites prepared by roll bonding

Al 6061/Ti-6Al-4V/Al 6061 laminated composites were fabricated by hot-roll bonding. The effect of rolling temperature and reduction on the microstructure and mechanical properties of Al/Ti/Al laminated composites was investigated. The results show that the Al/Ti/Al laminated composites exhibited a good Al/Ti interfacial bonding. The reduction ratio of Ti to Al layer decreased with increasing rolling temperature and reduction. The development of microstructure through the thickness of Al layer was inhomogeneous. The number of high-angle boundaries and the misorientation angle across low-angle boundaries increased as the thickness position moved towards the surface of Al layer from the interface of Al/Ti. The initial grains near the surface of Al layer were markedly elongated at a certain angle to the RD and then fragmented into the equiaxed fine grains at larger rolling reductions. This inhomogeneity of microstructure can be attributed to the effect of the friction between the roll and sheet surface and the uncoordinated deformation between Al and Ti layers. The deformation inhomogeneity increased with increasing rolling reduction. For the laminated composites fabricated with rolling reductions of 27% and 38%, the yield and tensile strength increased to a maximum value at about 400 °C and then decreased with increasing rolling temperature. The laminated composites fabricated with a 45% reduction possessed lower strength in the temperature range from 400 °C to 450 °C than those with a 38% reduction due to the fracture of Ti layer.