銅単結晶の変形段階IIにおける2次すべりの発生

Abstract

Corroborative evidence for the origin of generation of secondary slip at stage II in the stress-strain curve has been obtained by detailed analyses with the etch-pit technique in copper crystals. It is shown that a sudden occurrence of secondary slip at stage II is directly related to the formation of deformation bands, particularly to the building-up of kink-band walls that is, as reported previously, the trigger for the transition from stage I to II. Among secondary slip systems actually observed in the kink-band wall region, the operation of the cross slip system (S42) is of particular interest because of its Schmid factor being zero. This strongly suggests that the sudden generation of secondary slip is caused by the internal stress induced by primary main slip (S11) dislocations piled-up against the kink-band wall. From the calculation based on a pile-up model, it is understood that primary coplanar slip S13 and secondary systems such as critical main slip S31, conjugate main slip S21, critical coplanar slip S23 and cross slip S42 are subject to fairly large internal stresses due to the pile-up of S11 dislocations. Especially, the operation of S21 and S33 is important because of their interaction with S11 which leads to the formation of Lomer sessiles.