Crystal structures and textures in the hot-forged Ni-Mn-Ga shape memory alloysShow others and affiliations
2006 (English)In: Metallurgical and Materials Transactions. A, ISSN 1073-5623, E-ISSN 1543-1940, Vol. 37A, no 5, p. 1397-1403Article in journal (Refereed) Published
Abstract [en]
Three ferromagnetic shape-memory alloys with the chemical compositions of Ni53Mn25Ga22, Ni48Mn30Ga22, and Ni48Mn25Ga22Co5 were prepared by the induction-melting and hot-forging process. The crystal structures were investigated by the neutron powder diffraction technique, showing that Ni53Mn25Ga22 and Ni48Mn25Ga22Co5 have a tetragonal, I4/mmm martensitic structure at room temperature, while Ni48Mn30Ga22 has a cubic, L2(1) austenitic structure at room temperature. The development of textures in the hot-forged samples shows the in-plane plastic flow anisotropy from the measured pole figures by means of the neutron diffraction technique. Significant texture changes were observed for the Ni48Mn25Ga22Co5 alloy after room temperature deformation, which is due to the deformation-induced rearrangements of martensitic variants. An excellent shape-memory effect (SME) with a recovery ratio of 74 pct was reported in this Ni48Mn25Ga22Co5 polycrystalline alloy after annealing above the martensitic transformation temperature, and the "shape-memory" influence also occurs in the distributions of grain orientations.
Place, publisher, year, edition, pages
2006. Vol. 37A, no 5, p. 1397-1403
National Category
Engineering and Technology Other Materials Engineering
Identifiers
URN: urn:nbn:se:liu:diva-48093OAI: oai:DiVA.org:liu-48093DiVA, id: diva2:268989
2009-10-112009-10-112017-12-13