Stair‐rod Dislocations and Extended Barriers in the Body‐centered Cubic Lattice

The interaction of glissile extended dislocations on intersecting {112} planes in the bodycentered cubic lattice is considered. It is found that, for each axis of intersection of two {112} planes except 〈111〉, stair‐rod dislocations of Burgers vectors 1/3 〈001〉, 1/3 〈002〉, and 1/6 〈113〉 can be formed. Formulas for the widths of the extended dislocation barriers in isotropic b.c.c. materials are derived, and numerical results are presented for tungsten. It is concluded that, for a stacking fault energy of the order of 100 erg/cm 2 , extended dislocation barriers will occur in tungsten.