γ variant-sensitive deformation behaviour of Inconel 718 superalloy

Strengthening in Inconel 718 superalloy is derived from dislocation interaction with gamma '' precipitates, which exist in disk-shaped three possible orientation variants with their {100} habit plane normal to each other. The interactions between dislocations and gamma '' precipitates vary according to the gamma '' orientation variants, which makes the deformation behaviour complicated and difficult to reveal experimentally. In this work, gamma '' variant distributions of Inconel 718 samples were tailored by ageing heat treatment under either tensile or compressive stress. The gamma '' variant-sensitive deformation behaviours were then studied by in situ tensile tests via neutron diffraction at room temperature. It is demonstrated that yielding first takes place in grains oriented with <110> parallel to the loading direction. An identical lattice strain response to applied stress of both the y matrix and the gamma '' precipitates was observed during yielding, suggesting that dislocations shearing through the gamma '' precipitates is predominant at this stage. Variations in yield strength for samples with different gamma '' variant distributions were observed, which can be attributed to different strengthening that arises from interactions between dislocation and different gamma '' variants. (C) 2022 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.

Automated summary

In this study, the gamma '' variant distribution in Inconel 718 samples was tailored through ageing heat treatment, and the variant-sensitive deformation behavior was studied through in situ tensile tests using neutron diffraction. The results showed that the yield strength varied with different gamma '' variant distributions, which can be attributed to the interactions between dislocations and different gamma '' variants.