Microbands and microtwins associated with impact craters in copper and brass targets: the role of stacking fault energy

Deformation microbands coincident with {111} slip planes are observed to be associated with impact craters in large-grain (0.8 mm) copper (stacking fault energy [SFE] 80 mJ/m2) while microtwins coincident with {111} slip planes are observed in large-grain (∼1.1 mm) brass (70 Cu–30 Zn; SFE ∼10 mJ/m2). Taken together with other impact crater studies, there is solid evidence for a strong influence of SFE in the microband–microtwin transition.