The influence of additive manufacturing on Portevin-Le Châtelier (PLC) effect in Ni–Co-based superalloy
Ling Tang, Lei Xu, Yang Li, Jianping Tan, Changyun Li, Jinguo Li, Jingjing Liang, Chuanyong Cui, Xiaofeng Sun
Abstract
The microstructures and tensile properties of the Ni-Co-based superalloys made by additive manufacturing (AM) were investigated. The results revealed that both normal and inverse Portevin-Le Châtelier (PLC) effects were observed in AM Ni-Co-based superalloys. In addition, AM significantly inhibited the PLC effect, the average stress decrements for the cast and wrought (C&W) alloys with the same nominal compositions were more than ten times as large as those for the AM alloys when tested at 400 °C with a strain rate of 3×10-4 s-1. In the AM Ni-Co-based superalloys, type C serrations had connections with the inverse PLC effect. Transmission electron microscope (TEM) was performed to investigate the interactions of solute atoms, dislocations, stacking faults (SFs) and the γ′ phase for a deep insight into mechanisms of the PLC effects and clarifying the changes in serration types and the conversion from normal to inverse PLC effect.