Portevin-Le Chatelier effect, twinning-detwinning and disordering in an aged Ni-Cr-Mo alloy during large plastic deformation

Portevin-Le Chatelier (PLC) effects, twinning-detwinning and disordering phenomena in long-range ordered (LRO) phase strengthened Ni-Cr-Mo alloys during hot compression are reported and investigated. The results reveal that the PLC effects with type-C serrations occur in the solution-treated and aged alloys, and that the Pt2Mo-type LRO phase can increase the serration amplitude at the early stage of deformation. Only after the early stage of deformation, the twinning of aged alloy can be activated. However, the deformation twin and the Pt2Mo-type LRO phase are not stable during the severe deformation. The potential disordering process of the LRO phase is provided as the slipping of the dislocation on the two valid {111}< 110 > slip systems. The occurrence of the steps on the twin boundaries of the remanent deformation twins reveals that the detwinning mechanism is likely the dislocation-twin boundary interaction.