TWINNING DEFORMATION IN SINGLE CRYSTALS OF Cu-8 at%Al ALLOY.

Abstract

Twinning made and twinning stress in the alloy investigated were examined at minus 196C to room temperature as a function of crystal orientation. It was found that the twinning mode strongly depends not only on crystal orientation but on deformation temperature. Twins are generally nucleated along the slip planes with the maximum resolved shear stress at the intersections of the twinning planes and well-developed slip bands. The slip bands also act as obstacles to the growth of twins. Twins are formed along the cross slip planes as well as along the conjugate and primary slip planes at minus 196C. The twinning stress depends not only on the prestrain for twinning but on the twinning mode. The results are discussed with references to a twinning model proposed by the authors. 22 refs.