Figure 6 shows the cross‐sectional SEM images of the Al/Cu joints, and corresponding EPMA element mapping of Al and Cu for the (a) 23/20, (b) 25/28.6, (c) 25/15.4, and (d) 27/20.

Figure 6 shows the cross‐sectional SEM images of the Al/Cu joints, and
corresponding EPMA element mapping of Al and Cu for the (a) 23/20, (b) 25/28.6, (c)
25/15.4, and (d) 27/20.