NSUF 22-4415: Irradiation Effects on Unexpected Deformation-Induced Martensitic Phase Transformation in Ni-alloys
The objective of this project is to understand how irradiation-induced defects affect the surprising, previously unreported deformation-induced martensitic transformations recently observed in a Ni-based superalloy. The mechanical behavior of Ni-based alloys has always been attributed to conventional fcc deformation mechanisms: dislocation plasticity, localized dislocation channeling upon irradiation, and dislocation twinning in the presence of precipitates or at cryogenic temperatures. But our recent NSUF-supported work on unirradiated and 1 dpa neutron irradiated Ni-base Alloy 625 has revealed surprising room temperature deformation-induced fcc-to-hcp and fcc-to-bcc martensitic transformations previously unreported in Ni superalloys. The martensites nucleated in the irradiated material differ from those in the as-received material. This is consistent with previous research on steels, which show that the critical transformation stresses for epsilon-hcp and alpha’-bcc martensite variants are sensitive to irradiation-induced cavity (i.e., bubbles and void) configurations. We therefore hypothesize that irradiation-induced cavities similarly enhance the tendency for deformation-induced martensitic transformability of Ni alloys by activating epsilon and/or alpha’ transformations. To resolve our hypothesis, we propose an approach to conduct proton, helium, and proton+helium dual-beam irradiations on Alloy 625, with subsequent grain orientation-dependent nanoindentation and transmission electron microscopic (TEM) deformation microstructure characterization. Here, the proposed single- and dual-beam irradiations are specifically designed to enable us to decouple the role of cavities from dislocation loops on deformation-induced phase transformations. Examining different grain orientations will also enable us to link the phase transformation to critical resolved shear stress. Work will be conducted at the Michigan Ion Beam Laboratory (MIBL) and the Center for Advanced Energy Studies (CAES).
Informație Adițională
| Cîmp | Valoare |
|---|---|
| Awarded Institution | None |
| Embargo End Date | 2024-09-29 |
| Facility Tech Lead | Alina Montrose, Kevin Field, Mukesh Bachhav |
| Irradiation Facilities | Michigan Ion Beam Laboratory |
| NSUF Call | FY 2022 RTE 1st Call |
| PI | Caleb Clement |
| PIE Facilities | Microscopy and Characterization Suite |
| Project Member | Professor Janelle Wharry, Professor - University of Illinois (https://orcid.org/0000-0001-7791-4394) |
| Project Member | Dr. Caleb Clement, Materials Engineer - Westinghouse Electric Company (https://orcid.org/0000-0002-8757-3914) |
| Project Notes | Awarded on 06/14/2022 |
| Project Type | RTE |
| Publication | Ion Implantation-Induced Plastic Phenomena in Metallic Alloys Patrick Warren, Janelle Wharry, Caleb Clement, Yang Yang Journal of Materials None https://doi.org/10.1007/s11837-024-06418-4 |
| Publication | Unexpected deformation-induced martensitic phase transformations in Ni-Cr alloys and Ni-Cr-Fe alloys Janelle Wharry, Caleb Clement Materials Science & Engineering A 892 2024-03-01 https://www.sciencedirect.com/science/article/abs/pii/S0921509323014533 |
| RTE Number | 4415 |