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.

Automated summary

Portevin-Le Chatelier (PLC) effects, twinning-detwinning, and disordering phenomena were observed and investigated in long-range ordered (LRO) phase strengthened Ni-Cr-Mo alloys during hot compression. The results showed that the PLC effects with type-C serrations occurred in the solution-treated and aged alloys, with the Pt2Mo-type LRO phase increasing the serration amplitude at the early stage of deformation. However, twinning of aged alloy was only activated after the early stage of deformation, and deformation twins and the Pt2Mo-type LRO phase were not stable during severe deformation. The potential disordering process of the LRO phase was suggested to be dislocation slipping on the two valid {111}<110> slip systems, and detwinning mechanism was likely the dislocation-twin boundary interaction as indicated by steps on the twin boundaries of remanent deformation twins.