In Situ ТЕМ Observations of the Thermal Degradation of the Two Way Memory Effect in a Cu-Al-Be Alloy
Instituto de Investigaciones en Materales, U.N.A.M., Apdo Postal 70-360, 04510 México D.F., México
2 Centro de Investigaciones en Materiales Avanzados, León Tolstoi N° 166, 31109 Chihuahua, México
3 GEMPPM, INSA de Lyon, ERA 341 du CNRS, Bât. 502, 20 Avenue A. Einstein, 69621 Villeurbanne cedex, France
A Cu-Al-Be alloy with a martensitic transformation temperature (Ms) lower than room temperature, was trained to induce the two way memory effect (TWME) and the aging effects in austenitic phase were studied by in-situ observations in a Transmission Electron Microscope. The results show movements of dislocations at temperatures where the TWME deformation is well known to decrease after short aging times (about an hour). Since the Burgers vector of these dislocations does not change during aging, and precipitates have been not observed, we concluded that the TWME degrades as a result of modifications in the internal stresses field distribution associated with dislocation movements, that produces a more random orientation of martensitic plates on cooling.
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