Localized shear bands, with minute misorientations off the slip plane, caused sharp failures in Ni3Al single crystals that failed after elongations exceeding 70 to 80% in room-temperature tensile tests. An explanation for intense slip plane shear failure, consistent with prior experimental observations, was proposed. Prior electron microscopy evidence obtained by Horton, Baker and Yoo of decreasing antiphase-boundary energy in highly deformed slip bands was used to suggest a highly localized order-disorder transition. This shear-strain-induced slip-plane disordering provided the essential mechanism to lower the work-hardening rate to zero or negative values. A decreasing work-hardening rate sustained persistent shear localization, ultimately leading to failure. This mechanism was suggested to be applicable to other ordered crystals.

Mechanism of Intense Shear Failure in Ni3Al Single Crystals. Dao, M., Kad, B.K., Asaro, R.J.: Philosophical Magazine A, 1997, 75[2], 443-59