Revealing the role of strain rate during multi-pass compression in an advanced polycrystalline nickel base superalloy

Microstructure evolutions characterized by EBSD and TEM corresponding to different stages in the multi pass compression. (a) Initial microstructure shows the uniform and fine grain size and low dislocation density. (b) After being deformed to a strain of 0.3 under conditions of 1100 C/0.1 s− 1, high dislocation density and a considerable DRX grains are detected to generate along the initial grain boundaries. (c) After dwelling period, the dislocations are significantly consumed by SRX and grain growth, leading to a sight of new grains. (d) More uniform and finer grain size are obtained after the material is deformed to the one with a true strain of 0.693.701