Developing the Cu/Sn Multilayer Composite through Accumulative Roll Bonding (ARB): Investigating the Microstructural and Mechanical Features

In this research, multilayer Cu/Sn composites were produced for the first time with the accumulative roll bonding (ARB) method using the commercial pure Cu and Sn sheets in up to eight cycles. The microstructural and mechanical properties of the Cu/Sn composites were studied during various ARB cycles by field emission scanning electron microscopy (FESEM), elemental mapsand X- ray diffraction (XRD), as well as tensile and Vickers micro-hardness tests. The results revealed that the necking and rupturing of the layers take place after 2 and 3 cycles, respectively. The final microstructure consists of the uniform distribution of the hard copper fragments and wavy soft Sn matrix. XRD and FESEM results confirmed the formation of the intermetallic Cu6Sn5 compound after 6 cycles. The maximum tensile strength reached 290 MPa after one ARB cycle, which is around 1.4 and 13 times higher than that of the pure Cu and Sn, respectively; thereafter, it decreased and then increased up to 150 MPa in the 8th cycle. The hardness of the copper layers increased by rising the number of ARB cycles. The tensile fracture mode for Cu and Sn layers was ductile in all ARB cycles. Further dimples were observed in the copper layers.