**3.1 Working procedure**

The schematic explaining the process of roll bonding is shown in **Figure 6**. The strips to be roll bonded are initially cleaned thoroughly by acetone to remove the surface contaminate layer. The cleaned strips are scratch brushed using a wire brush. The wire brushing on any one side produces a rough surface which will help in bonding the sample in two ways. One strain hardens the surface forming a hard brittle cover layer, and the other is it brings the fresh virgin metal surface to open up. Now, the two scratched samples are stacked and clamped as shown in the **Figure 6**. The stacked samples are passed between the pair of rollers to produce bonding. The bonding between

**Figure 6.** *Schematic diagram of roll bonding process.*

the samples is possible only if the reduction given will be more than the threshold reduction [42]. It is feasible to heat the sheets near or above their recrystallization temperature to get improved bond strength.
