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Characteristics of microcrack initiation in CuNiAl shape memory alloy
Author(s) -
LU Y. H.,
QIAO L. J.,
CHU W. Y.
Publication year - 2002
Publication title -
fatigue and fracture of engineering materials and structures
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.887
H-Index - 84
eISSN - 1460-2695
pISSN - 8756-758X
DOI - 10.1046/j.1460-2695.2002.00519.x
Subject(s) - martensite , materials science , shape memory alloy , transmission electron microscopy , slip (aerodynamics) , alloy , composite material , dislocation , optical microscope , lüders band , microscopy , scanning electron microscope , crystallography , microstructure , optics , nanotechnology , chemistry , physics , thermodynamics
The mechanism of microcrack initiation in CuNiAl shape memory alloy was investigated through in situ tensile tests under optical microscopy, scanning electron microscopy and transmission electron microscopy. The results indicated that various martensite phases appeared first around a notch tip upon loading, and then microcracks initiated along the martensite/parent interface. The small martensite regions could transform back to the parent phase not only upon unloading but also upon loading or during crack propagation. There was no dislocation emission and motion before martensite formation. The slip bands formed after the crack had propagated a definite distance, and the microcracks nucleated and the cracks propagated either along the slip bands or the martensite/parent interface.