Second-order junctions and strain hardening in bcc and fcc crystals

Axial ternary junctions, which were recently discovered by Bulatov et al. [V.V. Bulatov et al., Nature 440 (2006) 1174], as well as zigzag ternary configurations, were classified according to crystallographic criteria in face-centered cubic (fcc) and body-centered cubic (bcc) metals. The determination of their average strength by dislocation dynamics simulations shows that ternary configurations induce a significant Taylor hardening in bcc crystals, but not in fcc crystals. In both cases, these configurations should enhance strain hardening through their contribution to the storage rate of dislocations.