Direct observation of twinning in tin lamellae

Lamellae of β-tin with 〈010〉 normals have been found to be suitable specimens for an electron microscopic study of twinning. The lamellae, formed by cellular precipitation in a lead-tin (5.5 at. %) alloy at room temperature, were isolated by chemical dissolution of the lead matrix. Twinning dislocations were observed on the incoherent boundary of a (301) deformation twin during its propagation in the lamella. The twinning dislocations tended to...