CROSS-SLIPPING PROCESS AND THE STRESS-ORIENTATION DEPENDENCE IN PURE COPPER

A new experiment has been performed, where an avalanche of cross-slip events is produced at yield, large enough to overtake other activated events like the cutting of trees by slip dislocations. This allows us to define a new cross-slip stress as the yield stress, more akin to cross-slipping than the usual τ3 is. Some intrinsic features of cross-slip in pure copper have been thus investigated. These include the intrinsic dependence of cross-slip on the stress orientation (the asymmetry tension-compression can be as high as 50%) from the same, given deformation substructure; and the measurement of the cross-slip activation volume, clearly smaller than forest volumes and in reasonable agreement with the expected width of screws. These new observations fit comprehensively only with the Friedel-Escaig cross-slip model, where the widening of the faulted ribbon is the driving force for cross-slipping, in a semi-quantitative basis. © 1979.