Mechanically induced disorder and crystallization process in Ni-Mn-In ball-milled alloys
[EN] High mechanical deformation has been induced in a Ni-Mn-In metamagnetic shape memory alloy by means of ball milling. The evolution of both the martensitic transformation and the magnetic properties associated to the microstructural variations has been characterized. The as-milled nanometric par...
| Autores: | , , , , , , , , |
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| Formato: | artículo |
| Fecha de publicación: | 2016 |
| País: | España |
| Recursos: | Universidad del País Vasco |
| Repositorio: | Addi. Archivo Digital para la Docencia y la Investigación |
| OAI Identifier: | oai:addi.ehu.eus:10810/63456 |
| Acesso em linha: | http://hdl.handle.net/10810/63456 |
| Access Level: | acceso abierto |
| Palavra-chave: | ni-mn-in ball milling crystallization atomic order nanoparticles |
| Resumo: | [EN] High mechanical deformation has been induced in a Ni-Mn-In metamagnetic shape memory alloy by means of ball milling. The evolution of both the martensitic transformation and the magnetic properties associated to the microstructural variations has been characterized. The as-milled nanometric particles display an amorphous structure with a frustrated magnetic state compatible with a canonical spin-glass. On heating, an abrupt crystallization process occurs around 500 K leading to a cubic B2 structure, which, in turn, does not show martensitic transformation. Modified Arrott plots point to competing long- and short-range magnetic couplings in the B2 structure. On further heating, a relaxation process takes place above 700 K concurrently with a B2-L21 atomic ordering, giving rise to an anomalous two-step thermal expansion. The combined effect of both processes makes possible the subsequent occurrence of a martensitic transformation, which takes place at the same temperature than in the bulk. The large relative-cooling-power linked to the magnetocaloric effect at the martensitic transformation in the annealed powder makes it interesting for practical applications of magnetic refrigeration at nanoscale. |
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