Crack-free Cu9Ni6Sn strips via twin-roll casting and subsequent asymmetric cryorolling

Abstract

CuNiSn alloys often generate cracks during traditional deformation. In this study, we report the development of the crack-free Cu9Ni6Sn strips by using twin-roll casting with subsequent asymmetric cryorolling. Although cracks appear in asymmetric hot-rolled and asymmetric room-temperature-rolled strips, no cracks were observed in asymmetric cryorolled (173 K and 83 K) strips. Electron back-scattered diffraction images indicate that deformation is relatively uniform for asymmetric cryorolled strips, with obvious shear bands appearing in asymmetric room-temperature-rolled and asymmetric hot-rolled strips. Energy dispersive spectroscopy images show that the segregation of Sn element appears near cracks in asymmetric hot-rolled and asymmetric room-temperature-rolled strips. The Sn element is uniformly distributed in asymmetric cryorolled strips. Uniform deformation, reduced Sn element segregation, and enhanced ductility at cryogenic temperature all contribute to the crack-free nature of the Cu9Ni6Sn strips prepared by asymmetric cryorolling.