Multi-layer faults on (112) planes and interatomic potentials in b.c.c. metals

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Abstract
The possibility of stable multi-layer stacking faults on (112) planes in b.c.c. metals has been studied by computer simulation. The relaxation method and the lithium potential used are described in the accompanying paper (Beauchamp 1978). γ-surface-type calculations have been performed for two-and three-layer faults. The possible extension of the results to all simple metals, and to transition metals described by polynomial model potentials, is discussed. For simple metals, no stable n-layer faults exist for n3, but a stable four-layer fault is found. The successive fault vectors are-b/6,-b/3,-b/3 and-b/6, where b = a½[1 11]. This can be regarded as a twin lamella limited by two twin boundaries in configuration 2. The total fault vector is-b, and thus a perfect dislocation could create this fault, n-layer faults with n  5 consist of a twin lamella with twin boundaries in configuration 1 or configuration 2. For most polynomial potentials, no stable n-layer faults are found for n  2, but faults with n  3 exist for which the total fault vector is not equal to-b. For other faults, the results are similar to those of simple metals.