A Discussion of Schmid Factors for Twinning in B.C.C. Crystals

AbstractThe Schmid Factors for the twelve {112}〈111〉 twinning systems in body-centred cubic crystals have been calculated. From these, the orientations that will give a crystal the greatest probability of twinning on one system only are derived. These orientations are [1.189, 2, 2] for crystals tested in compression and [1, 1.667, 2] for crystals tested in tension. As the maximum Schmid Factor for {l01}〈111〉 slip is high and the maximum Schmid Factor for twinning in tension is low at [1, 1.667, 2], it is concluded that testing in compression at [1.189, 2,2] will give the greatest probability of producing one, and only one, family of twins.