ABSTRACT
The boundaries introduced in metals play crucial roles in mechanical behaviors. Here the effect of gradient boundaries on mechanical behavior was investigated in a laminated Cu-30Zn sample composed of coarse-grained and ultrafine-grained layers. Tensile tests revealed a superior strength-ductility combination with extraordinary strengthening and work hardening. This chapter presents a CG/ultrafine-grained (UFG) laminate structure with two discrete gradient boundaries. The configuration and evolution of 3D strain gradient near gradient boundary were quantitatively visualized using height contour measurement and in-situ digital image correlation (DIC). The formation of strain gradient and its effect on strengthening and strain hardening behaviors will be discussed. Dog-bone shaped tensile specimens with a gauge length of 18 mm were machined parallel to the processing direction in as-FSP processed plate. An enhanced strength-ductility synergy was found in the hetero-structured laminate, which can be primarily attributed to the extraordinary strengthening and work hardening effects originated from gradient boundaries.
