| Summary: | 碩士 === 國立臺灣大學 === 應用力學研究所 === 97 === Our team proposed a framework based on constrained theory, to establish evolution of microstructure in martensitic polycrystalline films. In this theory, the evolution converges by energy restraining gradually. We observed the arrangement of the microstructure of the bottom energy. We study the microstructure according to the arrangement as well as its evolutionary process of polycrystalline, and compute the stress with fast algorithm (FFT). We design a simple model which is two-dimensional two crystals film, and give one angle θ degree rotation to distinguish from another, we observe the compatibility of the grain boundary.
In addition, we carry on the numerical simulation in another case, the thin film model is exerted by each kind of strain. We draw up with the strain and the result of
simulation, and keep observing the difference between the single crystal and poly crystal micro structure.
In poly crystal, the grain micro structure change depend on the θ degree rotation, but the grain boundary lack for compatibility, for all this, there is no strain of hole
model attribute to the evolution of micro structure inside, under the bottom energy.
The exerted strain and the variant can be drawn up the hysteresis loop. We have compared the single crystal and the poly crystals in the different thickness, and find
the the influence of thickness is not conspicuous. And in the same other conditions, the crystals are more complex, more exerted strain is needed to urge the switch.
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