日本金属学会誌

J. Japan Inst. Metals, Vol. 54, No. 8 (1990),
pp. 861-869

Self-Accommodation Structure in the Ti-Ni-Cu Orthorhombic Martensite

Youichi Watanabe1, Toshio Saburi2, Yutaka Nakagawa3 and Soji Nenno4

1Graduate Student, Osaka University, Suita
2Dapartment of Materials Science and Engineering, Faculty of Engineering, Osaka University, Suita
3Undergraduate Student, Osaka University, Suita. Present address: Sumitomo Metal Ind., Ltd., Amagasaki
4Department of Materials Science and Engineering, School of Science and Engineering, Teikyo University, Utsunomiya

Abstract:

Self-accommodation process and the resulting structure of the orthorhombic martensite in a Ti-Ni-Cu shape memory alloy were investigated.
Observations of the self-accommodation process of habit plane variants of the orthorhombic Ti-Ni-Cu martensite were made by transmission electron microscopy, and the three-dimensional configuration of the variants resulting from self-accommodation was analyzed.
The results obtained are as follows.
(1) The fundamental unit of the self-accommodation structure in three-dimensions is cuboidal, consisting of six different variants. This structure appears to be a triangular when observed in the <111>P direction (P: Parent).
(2) The six variants are twin related with each other and two types of twin relations exist among them. One is the (111)M[211]M type I twin and the other is the (011)M[011]M compound twin (M: Martensite).
Then, on the basis of the observed relations among the variants the deformation process of the orthorhombic martensite was discussed.


(Received 1990/4/14)

Keywords:

martensitic transformation, shape memory alloy, titanium-nickel alloy, titanium-nickel-copper alloy, electron microscopy, self-accommodation, variant configuration

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