Ni/Ti and Ni/Al Laminated Composites Produced by ARB and Annealing: Microstructural Aspects

Accumulative roll bonding (ARB) is a combination of forming and bonding processes. So, this is a high promising technique to produce bulk solid materials composed of more than one constituent. ARB has been applied to strengthen metals and to produce laminated metal-metal or nonmetal-metal composites, e.g. intermetallic composites, shape memory alloys or reactive foils [[1, 2]]. Since ARB is performed at room temperature, the formation of new phases can be avoided. This technique is also capable of mass production and it can fabricate thick foils, using simple and cheap equipment. This essay compares two bimodal multilayer foils: Ni/Ti and Ni/Al. Input materials include foils of 99.98 wt% Ni - 125 µm thick, 99.00 wt% Al - 200 µm thick and 99.6 wt% Ti - 200 µm thick. Rolling was done with a strain rate of 20 s-1 at room temperature. Rolled batches after 4 and 10 cycles were characterized by optical and scanning electron microscopies. Energy dispersive spectroscopy (EDS) as chemical analysis technique was used to identify phases evolved in the multilayers during processing. Electron backscattering diffraction (EBSD) technique also assisted phase identification.