Experimental observation of vacancy-assisted martensitic transformation shift in Ni-Fe-Ga alloys
Positron annihilation lifetime spectroscopy is used to experimentally demonstrate the direct relationship between vacancies and the shift of the martensitic transformation temperature in a Ni55Fel7Ga28 alloy. The evolution of vacancies assisting the ordering enables shifts of the martensitic transfo...
| Authors: | , , , , , , , |
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| Format: | article |
| Status: | Published version |
| Publication Date: | 2019 |
| Country: | España |
| Institution: | Universidad Pública de Navarra |
| Repository: | Academica-e. Repositorio Institucional de la Universidad Pública de Navarra |
| OAI Identifier: | oai:academica-e.unavarra.es:2454/35939 |
| Online Access: | https://hdl.handle.net/2454/35939 |
| Access Level: | Open access |
| Keyword: | Ferromagnetism Martensitic phase transition Heusler alloy Density functional theory Differential scanning calorimetry Electron-correlation calculations Positron annihilation spectroscopy |
| Summary: | Positron annihilation lifetime spectroscopy is used to experimentally demonstrate the direct relationship between vacancies and the shift of the martensitic transformation temperature in a Ni55Fel7Ga28 alloy. The evolution of vacancies assisting the ordering enables shifts of the martensitic transformation up to 50 K. Our results confirm the role that both vacancy concentration and different vacancy dynamics play in samples quenched from the L2(1) and B2 phases, which dictate the martensitic transformation temperature and its subsequent evolution. Finally, by electron-positron density functional calculations V-Ni is identified as the most probable vacancy present in Ni55Fe17Ga28. This work evidences the capability of vacancies for the fine-tuning of the martensitic transformation temperature, paving the way for defect engineering of multifunctional properties. |
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