The stability of an infinitely long <111> screw super-dislocation that was dissociated into antiphase boundary-coupled super-partials on {110}, {112} or a combination of both, was analyzed within the approximations of linear elasticity theory. In the absence of an applied load, the variation in the configurational energy of the dislocation pair in equilibrium was studied analytically as a function of 2 basic material parameters. These were the elastic anisotropy parameter along <111>, M, and ratio of the {112} to the {110} antiphase boundary energy. It was found that, although there was no torque on the screw partials on both {110} and {112}, the torque was present at intermediate angular positions and acted in a direction which stabilized {112} dissociation and destabilized {110} dissociation. In general, dissociation on {112} was energetically favored if the ratio of the {112} to the {110} antiphase boundary energy was greater than M1/3. Since M was greater than unity in anisotropic elastic media, and ranged from 1.09 for FeAl to 1.64 for AuCd, favorable {112} dissociation did not require the antiphase boundary energy for {112} to be less than that for {110}. In the case of compounds for which M was greater than 1.22, the screw super-dislocation could dissociate into stable non-planar configurations with the antiphase boundary lying partly on {110} and partly on {112}; forming a locked structure.

Y.Q.Sun: Acta Metallurgica et Materialia, 1995, 43[10], 3775-82