Crystal structures and textures in the hot-forged Ni-Mn-Ga shape memory alloys

Cong, D YSchool of Materials and Metallurgy, Northeastern University, Shenyang, China (author)

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.

Wang, YandongKey Lab for Anisotropy & Texture of Mater., Northeastern Univ., Shenyang, China (author)
Peng, RuLinköpings universitet,Konstruktionsmaterial,Tekniska högskolan(Swepub:liu)rupe37 (author)
Zetterström, PThe Studsvik Neutron Research Laboratory, Uppsala University (author)
Zhao, XSchool of Materials and Metallurgy, Northeastern University, Shenyang, China (author)
Liaw, P KDept of Materials Science and Eng, The University of Tennessee, Knoxville, USA (author)
Zuo, LSchool of Materials and Metallurgy, Northeastern University, Shenyang, China (author)
School of Materials and Metallurgy, Northeastern University, Shenyang, ChinaKey Lab for Anisotropy & Texture of Mater., Northeastern Univ., Shenyang, China (creator_code:org_t)

In:Metallurgical and Materials Transactions. A37A:5, s. 1397-14031073-56231543-1940

By the author/editor: Cong, D Y; Wang, Yandong; Peng, Ru; Zetterström, P; Zhao, X; Liaw, P K; show more...; Zuo, L; show less...

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