Fracture of Shape Memory CuAlNi Single Crystals
by
Loughran (Vasko), G. M., Shield, T. W., and Leo, P. H.
in
International Journal of Solids and Structures, 40(2), pp. 271-294, 2003.
Category: Journal Article
Keywords: fracture, single crystal, shape memory
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Abstract:
The fracture behavior of shape memory CuAlNi single crystals loaded in tension is studied. Specimens cut from a single crystal are notched and loaded in tension until final fracture. Eight different crystallographic orientations of the notch and tensile axes are considered. The stress field at the notch tip triggers a cubic to orthorhombic phase transition in the crystal, which results in a set of twinned martensite plates emanating from the notch tip. As loading increases, a crack forms and grows off the notch tip, with the martensite plates continuing to appear at the growing crack. Details of the crack growth depend strongly on both the type of martensitic microstructure that forms and how this microstructure interacts with the growing crack. In one group of orientations a distinct transformation zone forms along one flank of the crack and the motion of this zone is directly connected to the crack growth. In a second group of orientations, the microstructure formation is not as strongly tied to the crack. Interestingly, in all specimens studied, the final crack direction is approximately 80 degrees from the direction of the martensite plates.
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