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Crystallographic features during martensitic transformation in Ni-Mn-Ga ferromagnetic shape memory alloys

journal contribution
posted on 2008-01-01, 00:00 authored by Daoyong Cong, Y Zhang, C Esling, Y Wang, X Zhao, L Zuo
The martensitic transformation crystallography in two Ni 53Mn25Ga22 (at. %) ferromagnetic shape memory alloys (FSMAs) was investigated by means of misorientation calculation and pole figure analysis based on the orientation of the martensitic lamellae obtained from electron backscattered diffraction (EBSD) measurements. In the alloy that was first annealed at 1073K for 4h, and then cooled to 473K at ~4K/min and held for 30min, followed by cooling to room temperature at ~10K/min, there are only two kinds of differently orientated martensitic lamellae with a misorientation angle of ~82° distributed alternatively in each initial austenite grain. There is a compound twinning orientation relationship between the two lamellae. The prevalent orientation relationship between austenite and martensite is Kurdjumov-Sachs (K-S) relationship with (111)A//(10I)M, [1-10]a//[11-1]m. In the alloy that was annealed at 1173K for 4h followed by furnace cooling, nanoscale twins inside the martensitic lamellae were observed and the orientation relationships both between the nanotwins within one lamella and between the nanotwins in two neighboring lamellae were determined. The results presented in this paper will enrich the crystallographic data of the FSMAs and offer useful information for the development of novel FSMAs with optimal performances.

History

Journal

Materials processing and texture : ceramic transactions

Volume

200

Pagination

397 - 403

Publisher

John Wiley and Sons

Location

Hoboken, N. J.

ISSN

1042-1122

Language

eng

Publication classification

C1.1 Refereed article in a scholarly journal

Copyright notice

2009, The American Ceramic Society

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