Competition between invariant habit plane and compatible junction plane in TiNb-based shape memory alloy

Composition dependence of the compatibility condition at junction plane (JP) (interface between habit plane variants (HV)) was evaluated by geometrically non-linear theory of martensite in Ti-Nb-Al shape memory alloys that have β (cubic) to α” (C-orthorhombic) martensitic transformation. The kinematic compatibility (KC) condition requires non-zero rotation of HV to form compatible JP; the angle of this rotation is termed θ. This means that the invariant habit plane (HP) and the compatible JP are not formed simultaneously. It turned out that twelve types of θ exist depending on the pair of HV. Composition dependence of each type of θ was systematically investigated. The previous results of transmission electron microscopy observations were also discussed in terms of the present results.

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Incompatibility of Martensite Variant Clusters in Self-accommodation Microstructure in Ti-Ni-Pd High Temperature Shape Memory Alloy

MRS Proceedings ◽

10.1557/opl.2015.148 ◽

2015 ◽

Vol 1760 ◽

Author(s):

Takeshi Teramoto ◽

Masaki Tahara ◽

Hideki Hosoda ◽

Tomonari Inamura

Keyword(s):

High Temperature ◽

Shape Memory Alloy ◽

Shape Memory ◽

Habit Plane ◽

Nonlinear Theory ◽

Geometrically Nonlinear ◽

Martensite Variant ◽

Geometrically Nonlinear Theory ◽

Electron Backscattering Diffraction ◽

Diamond Cluster

ABSTRACTThe formation frequency of habit plane variant (HPV) clusters in Ni-25Pd-50Ti shape memory alloy was analyzed using electron backscattering diffraction (EBSD) on the basis of the geometrically nonlinear theory of martensite. Two types of cluster, diamond and wedge, were most commonly observed. The ratio of the formation frequency of the diamond to wedge clusters was approximately 1 : 3, whereas the rotation to keep the kinematic compatibility (KC) condition, θ *, was 3.9° and 0.0032°, respectively. The ratio of the formation frequency is quantified by the value of θ * which is an indicator of the incompatibility of the cluster. The origin of the diamond cluster is discussed based on the degree of incompatibility.

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Self-Accommodation Morphology in Ti-Nb-Al Shape Memory Alloy

Materials Science Forum ◽

10.4028/www.scientific.net/msf.654-656.2154 ◽

2010 ◽

Vol 654-656 ◽

pp. 2154-2157 ◽

Cited By ~ 3

Author(s):

Tomonari Inamura ◽

Hideki Hosoda ◽

Hiroyasu Kanetaka ◽

Hee Young Kim ◽

Shuichi Miyazaki

Keyword(s):

Electron Microscopy ◽

Transmission Electron Microscopy ◽

Shape Memory Alloy ◽

Shape Memory ◽

Habit Plane ◽

The Self ◽

The Other ◽

Conventional Transmission Electron Microscopy ◽

Transmission Electron

The self-accommodation microstructure of a -titanium shape memory alloy (SMA) was investigated by conventional transmission electron microscopy (CTEM) observation. There were two distinct minimum units for the self-accommodation microstructure. One was the V-shaped pair of two habit plane variants that were bounded by the {111}TypeI twin as reported in some previous studies. The other was the bundle of the two habit plane variants that were bounded by the <211>TypeII twin. The later one had not been recognized as the self-accommodation microstructure in -titanium SMAs.

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