GENERALIZED STACKING-FAULT ENERGETICS AND DISLOCATION PROPERTIES - COMPACT VERSUS SPREAD UNIT-DISLOCATION STRUCTURES IN TIAL AND CUAU

We present a general scheme for analyzing the structure and mobility o f dislocations based on solutions of the Peierls-Nabarro model with a two component displacement field and restoring forces determined from the ab initio generalized stacking fault energetics (i.e., the so-call ed gamma surface). The approach is used to investigate dislocations in L1(0) TiAl and CuAu; predicted differences in the unit dislocation pr operties are explicitly related with features of the gamma-surface geo metry. A unified description of compact, spread and split dislocation cores is provided with an important characteristic ''dissociation path '' revealed by this highly tractable scheme. [S0163-1829(98)03342-6].