Fundamental Mechanisms in Stress-Aided Variant Selection of Nanoscale Precipitation
Project Overview
Nickel-based superalloys possess combined high strength and corrosion resistance during service at elevated temperatures. They have been widely used in high-performance combustion engines, such as gas turbines, thermal and nuclear power plants. This program aims to understand and control the orientation of precipitates with respect to the alloy matrix in a novel nickel-based superalloy to achieve anisotropic strengthening.
Key findings:
•Stress-aided aging has been conducted and compared with conventional aging. The former has resulted in the formation of nanoscale precipitates in parallel to each other during growth and coarsening.
•The mechanism is believed to be the reduction of elastic strain energy caused by the precipitate/matrix lattice mismatch. This is also confirmed from the computational framework based on phase field model.
•This finding paves the way for fabricating the nickel-based single crystal and applying stress-aided aging for anisotropic strengthening Using Ni-based alloys as an example, the formation mechanisms of variant selection of coherent nanometer-sized precipitates at the nucleation and early growth stage, and the corresponding modulated mechanical properties will be investigated.
Publications
- J. Song, X. Jimenez, C. Russel, A. To, Y. Fu*, “Unusually High Room and Elevated-Temperature Tensile Properties Observed in Direct Aged Wire-Arc Directed Energy Deposited Inconel 718”. Scientific Report 13 (2023) 19235.
- J. Song, Y. Fu*, “First-principles calculation of stacking fault energies in Ni2(Cr, Mo)”, Materials Today Communication, 34 (2023) 105447.
- J. Song*, R. Field, A. Clarke, Y. Fu*, M. Kaufman, "Variant selection of intragranular Ni2(Mo,Cr) precipitates in the Ni-Mo-Cr-W alloy", Acta Materialia 165 (2019) 362-372.