Effects of Sn on defect structures in high-speed deformed Ni–Sn alloy

Defect structures in compressed and fractured pure Ni and Ni–2 at.%Sn alloy were investigated. The dislocation cell size of high-speed compressed Ni was smaller than that of low-speed compressed Ni. In Ni–Sn, the cell structure was small and independent of compression speed. The effect of solute Sn was very strong, and Sn trapped a high density of dislocations. At the saw-tooth-like fracture tips formed by high-speed elongation, the observed dislocation density was low in both metals, but was lower in Ni than in Ni–Sn. The number of stacking fault tetrahedra (SFTs) formed at the tips was almost the same in Ni as in Ni–Sn. Because the density of the dislocations was very low despite the strong effect of solute Sn, and because the density of formed SFTs was almost the same in both metals at the saw-tooth-like fracture tips, the formation of SFTs likely involves a dislocation-free mechanism during high-speed deformation.