NSUF 16-644: In situ study of defect accumulation in Ti-6Al-4V under heavy ion irradiation: Influence of the microstructure and temperature
In previous studies, a dual dose and temperature dependence was observed in the mechanical properties of Ti-6Al-4V irradiated with neutrons[1], protons[3] and swift heavy ions[4]: Samples irradiated at higher temperature exhibited higher hardening at higher doses. The microstructure of irradiated Ti-6Al-4V was investigated by Tähtinen et al. [1] (Neutron irradiation at 350°C and at 0.3 dpa) and Wilkes et al.[2] (irradiation with 17.5 MeV Cu4+ at 250°C, 350°C and 450°C at 1.5 dpa). At high temperature, the microstructure of irradiated Ti-6Al-4V is characterized by V-rich precipitates [1]or ß phase precipitation [2] at doses between 0.3 and 1.5 dpa. However, at low temperature, TEM investigations showed mainly a high density of dislocation loops [1]. The microstructure evolution induced different obstacles to the dislocation motion and could explain this higher hardening at high temperature and doses. In these studies, only the final irradiated microstructure at a certain damage level was investigated which leaves gaps in our understanding of the damage mechanisms. In-situ TEM irradiation offers the unique capability to investigate the evolution of the irradiation damage through continual imaging and observation. It allows for quantitative and qualitative microstructural studies. Using IVEM-Tandem Facility at Argonne National Laboratory with its in-situ TEM irradiation capability could improve our understanding of the influence of the microstructure and the thermos-mechanical processing on the irradiation damage in Ti-6Al-4V. We are proposing to irradiate 4 TEM samples (3 mm disks) with 1 MeV Kr2+ ions to different damage levels ranging from 0.008 dpa to 1 dpa [7] and at 25°C. The Ti-6Al-4V samples have of the four different microstructures: PM rolled, as received DMLS, DMLS followed by hot isostatic pressing (hip) and DMLS then heat treated for 2 hours at a temperature of 1020°C. This is a continuation of the proposal (16- 611) where TEM samples were irradiated at 350°C. The range of Kr ions in a Ti-6Al-4V target estimated with SRIM is ~ 389 nm. The thickness of the TEM foils (~100 nm) would allow for a homogeneous irradiation of the whole thickness.The TEM samples will be characterized before irradiation at Michigan State University. The sample preparation costs would be covered by MSU. The machine time was estimated based on SRIM calculations for a damage rate of ~ 10-3 dpa.s-1. The needed machine time is 3 days.
Additional Info
| Field | Value |
|---|---|
| Abstract | In previous studies, a dual dose and temperature dependence was observed in the mechanical properties of Ti-6Al-4V irradiated with neutrons[1], protons[3] and swift heavy ions[4]: Samples irradiated at higher temperature exhibited higher hardening at higher doses. The microstructure of irradiated Ti-6Al-4V was investigated by Tähtinen et al. [1] (Neutron irradiation at 350°C and at 0.3 dpa) and Wilkes et al.[2] (irradiation with 17.5 MeV Cu4+ at 250°C, 350°C and 450°C at 1.5 dpa). At high temperature, the microstructure of irradiated Ti-6Al-4V is characterized by V-rich precipitates [1]or ß phase precipitation [2] at doses between 0.3 and 1.5 dpa. However, at low temperature, TEM investigations showed mainly a high density of dislocation loops [1]. The microstructure evolution induced different obstacles to the dislocation motion and could explain this higher hardening at high temperature and doses. In these studies, only the final irradiated microstructure at a certain damage level was investigated which leaves gaps in our understanding of the damage mechanisms. In-situ TEM irradiation offers the unique capability to investigate the evolution of the irradiation damage through continual imaging and observation. It allows for quantitative and qualitative microstructural studies. Using IVEM-Tandem Facility at Argonne National Laboratory with its in-situ TEM irradiation capability could improve our understanding of the influence of the microstructure and the thermos-mechanical processing on the irradiation damage in Ti-6Al-4V. We are proposing to irradiate 4 TEM samples (3 mm disks) with 1 MeV Kr2+ ions to different damage levels ranging from 0.008 dpa to 1 dpa [7] and at 25°C. The Ti-6Al-4V samples have of the four different microstructures: PM rolled, as received DMLS, DMLS followed by hot isostatic pressing (hip) and DMLS then heat treated for 2 hours at a temperature of 1020°C. This is a continuation of the proposal (16- 611) where TEM samples were irradiated at 350°C. The range of Kr ions in a Ti-6Al-4V target estimated with SRIM is ~ 389 nm. The thickness of the TEM foils (~100 nm) would allow for a homogeneous irradiation of the whole thickness.The TEM samples will be characterized before irradiation at Michigan State University. The sample preparation costs would be covered by MSU. The machine time was estimated based on SRIM calculations for a damage rate of ~ 10-3 dpa.s-1. The needed machine time is 3 days. |
| Award Announced Date | 2016-04-11T00:00:00 |
| Awarded Institution | None |
| Facility | None |
| Facility Tech Lead | Wei-Ying Chen |
| Irradiation Facility | None |
| PI | Carl Boehlert |
| PI Email | [email protected] |
| Project Type | RTE |
| RTE Number | 644 |