Crystal structures and textures in the hot-forged Ni-Mn-Ga shape memory alloys
Data(s) |
01/05/2006
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Resumo |
Three ferromagnetic shape-memory alloys with the chemical compositions of Ni<sub>53</sub>Mn<sub>25</sub>Ga<sub>22</sub>, Ni<sub>48</sub>Mn<sub>30</sub>Ga<sub>22</sub>, and Ni<sub>48</sub>Mn<sub>25</sub>Ga<sub>22</sub>Co<sub>5</sub> were prepared by the induction-melting and hot-forging process. The crystal structures were investigated by the neutron powder diffraction technique, showing that Ni<sub>53</sub>Mn<sub>25</sub>Ga<sub>22</sub> and Ni<sub>48</sub>Mn<sub>25</sub>Ga<sub>22</sub>Co<sub>5</sub> have a tetragonal, 14/mmm martensitic structure at room temperature, while Ni<sub>48</sub>Mn<sub>30</sub>Ga<sub>22</sub> has a cubic, L2<sub>1</sub> 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 Ni<sub>48</sub>Mn<sub>25</sub>Ga<sub>22</sub>Co<sub>5</sub> 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 Ni<sub>48</sub>Mn<sub>25</sub>Ga<sub>22</sub>Co<sub>5</sub> polycrystalline alloy after annealing above the martensitic transformation temperature, and the “shape-memory” influence also occurs in the distributions of grain orientations. <br /> |
Identificador | |
Idioma(s) |
eng |
Publicador |
Springer New York LLC |
Relação |
http://dro.deakin.edu.au/eserv/DU:30047878/cong-crystalstructures-2006.pdf http://dx.doi.org/10.1007/s11661-006-0084-0 |
Palavras-Chave | #anisotropy #austenite #composition #crystal structure #deformation #ferromagnetic materials #plastic flow #polycrystalline materials #shape memory effect #textures |
Tipo |
Journal Article |