Twinning Deformation in Single Crystals of Cu-8 at%Al Alloy

Abstract

Twinning mode and twinning stress in Cu-8 at%Al single crystals have been examined as a function of crystal orientation in the temperature range from −196°C to room temperature. The main results obtained are summarized as follows: (1) Twinning mode strongly depends not only on the crystal orientation but on the deformation temperature. (2) Twins are generally nucleated along the slip planes with the maximum resolved shear stress at the intersections between the twinning planes and the well-developed slip-bands. Those well-developed slip-bands also act as obstacles for the growth of twins. (3) Twins are formed along the cross slip-planes as well as along the conjugate and primary slip-planes at −196°C. (4) The twinning stress depends not only on the prestrain for the twinning but on the twinning mode.
The results are discussed with a twinning model proposed by the present authors.