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Precursor effects of martensitic transformations in Ti‐based alloys studied by electron microscopy with energy filtering
Author(s) -
Murakami Y.,
Shibuya H.,
Shindo D.
Publication year - 2001
Publication title -
journal of microscopy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.569
H-Index - 111
eISSN - 1365-2818
pISSN - 0022-2720
DOI - 10.1046/j.1365-2818.2001.00913.x
Subject(s) - materials science , microstructure , martensite , electron microscope , scattering , dark field microscopy , condensed matter physics , microscopy , diffusionless transformation , electron , lattice (music) , optics , resolution (logic) , crystallography , molecular physics , physics , chemistry , composite material , acoustics , quantum mechanics , artificial intelligence , computer science
Precursor effects of martensitic transformations in two well‐known shape memory alloys, Ti 50 Ni 48 Fe 2 and Ti 50 Pd 34 Fe 16 , were studied extensively by energy‐filtered electron microscopy, including in‐situ observations, and high‐resolution electron microscopy. Energy‐filtered dark‐field images, where weak diffuse scattering was utilized, clearly showed the microstructure in the premartensitic state of Ti 50 Ni 48 Fe 2 . Tiny domains observable in this state were close to spherical rather than thin and slender, and the temperature dependence of the domain‐like structure was clarified by the in‐situ observations. It was found that Ti 50 Pd 34 Fe 16 exhibited a domain‐like structure similar to that of Ti 50 Ni 48 Fe 2 , which was attributed to a transverse lattice displacement. High‐resolution images of Ti 50 Pd 34 Fe 16 showed that a domain was coupled with other ones with different orientations of distortion, so as to reduce the total strain due to their formations. Furthermore, effects of including a fundamental reflection, in addition to the diffuse scattering, on dark‐field images were discussed based on the observations and the image processing.