Elastic and Dissepaive Energies in Phase Transformation of Cu-based Shape Memory Alloys
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The amazing shape memory property of shape memory alloys (SMAs) attracted the attention of many scientists and engineers in the last decades, because of a wide range of important technical applications. Many models have been published for the description of the shape memory property as well as for the determination of critical parameters important for the technology. Furthermore, many experiments have also been carried out to understand the basic mechanisms and the details of the shape memory effect (SME).
In my thesis - after an introduction containing the most important definitions, notations and terminologies - I will describe in details one of these models (developed in Debrecen) and use it for analysis of the experimental results obtained in Cu based single and polycrystalline samples (CuAl(11.5wt%)Ni(5.0wt%) and CuAl(11,6wt%)Be(0.36wt%) respectively). By using this model I was able to calculate the non chemical (elastic and dissipative) free energy terms and their contributions to the martensite/austenite phase transformation and could also obtain the stress and temperature dependence of these energies. Furthermore, I also determined the dependence of the above energies on the number of thermal as well as mechanical cycles.