NSUF 20-2989: Insights into the forced chemical redistribution in multi-layered Zr/Nb nanocomposites under heavy dose ion irradiation
This user project is aimed to investigate the intrinsic length scale effects on the evolution of chemical distribution in the mixed layer of ion irradiated Zr/Nb multilayers. Displacement cascades in target materials by energetic incident ions triggers ballistic collisions with the target atoms and local thermal spikes. The formation of many cascade-induced thermal spikes drives the transient diffusion processes within these spikes and mixing at the atomic scale. However, studies suggest that extent of mixing by diffusion is biased by chemical affinity between the species which could result in local compositional fluctuations and demixing. In this work, for the first time, we would employ the atom probe tomography technique to perform the local compositional analyses of mixed layer formed under high dose ion irradiation in mechanically processed Zr/Nb multilayers. The roll bonding processed Zr/Nb nanocomposites with the average individual layer thicknesses of 80nm, 40nm, 15nm that were irradiated with 7 MeV Zr2+ ions at 500°C will be used for this study. For the APT study, needles encompassing the mixed layer in the irradiated region and needles from unirradiated region will be fabricated with the focused ion microscope. The results will provide atomic scale information on the extent of mixing under irradiation and would offer fundamental insights on the contributions of various competing processes like thermal spike-induced diffusion and thermodynamic forces on mixing in immiscible systems. The APT experiments also shed light on the influence of layer thickness on the local compositional distribution in multilayers. The outcomes of the work will be presented at major international conferences in the field and the work is expected to yield high-quality journal publications.
Additional Info
| Field | Value |
|---|---|
| Abstract | This user project is aimed to investigate the intrinsic length scale effects on the evolution of chemical distribution in the mixed layer of ion irradiated Zr/Nb multilayers. Displacement cascades in target materials by energetic incident ions triggers ballistic collisions with the target atoms and local thermal spikes. The formation of many cascade-induced thermal spikes drives the transient diffusion processes within these spikes and mixing at the atomic scale. However, studies suggest that extent of mixing by diffusion is biased by chemical affinity between the species which could result in local compositional fluctuations and demixing. In this work, for the first time, we would employ the atom probe tomography technique to perform the local compositional analyses of mixed layer formed under high dose ion irradiation in mechanically processed Zr/Nb multilayers. The roll bonding processed Zr/Nb nanocomposites with the average individual layer thicknesses of 80nm, 40nm, 15nm that were irradiated with 7 MeV Zr2+ ions at 500°C will be used for this study. For the APT study, needles encompassing the mixed layer in the irradiated region and needles from unirradiated region will be fabricated with the focused ion microscope. The results will provide atomic scale information on the extent of mixing under irradiation and would offer fundamental insights on the contributions of various competing processes like thermal spike-induced diffusion and thermodynamic forces on mixing in immiscible systems. The APT experiments also shed light on the influence of layer thickness on the local compositional distribution in multilayers. The outcomes of the work will be presented at major international conferences in the field and the work is expected to yield high-quality journal publications. |
| Award Announced Date | 2020-02-05T14:12:11.43 |
| Awarded Institution | None |
| Facility | None |
| Facility Tech Lead | Yaqiao Wu |
| Irradiation Facility | None |
| PI | Madhavan Radhakrishnan |
| PI Email | [email protected] |
| Project Type | RTE |
| RTE Number | 2989 |