Dresden 2003 – wissenschaftliches Programm
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M: Metallphysik
M 41: Postersitzung
M 41.3: Poster
Donnerstag, 27. März 2003, 14:30–16:30, HSZ
Orientation of Ni4Ti3 precipitates in uniaxial loaded NiTi single crystals — •Klaus Neuking, Alejandro Yawny, Mark Carroll, Jens Michutta, Christoph Somsen, and Gunther Eggeler — Werkstoffwissenschaft - Ruhr-Universität Bochum
Shape memory alloys constitute a associated type of material exhibiting distinctive stress-strain-temperature behaviour. NiTi represents the most important class of these alloys because of its wide range of applications. Optimal use and performance of the material, however, requires thorough understanding of some basic aspects that control final properties. Precipitation processes in NiTi alloys are essential in this sense, affecting both the mechanical as well as the functional characteristics. In the present work the precipitation of Ni4Ti3 in NiTi single crystals with a nominal Ni-concentration of 50.8 at% is studied. The single crystals were produced via the Bridgman technique by remelting a polycrystalline NiTi alloy previously cast in an induction furnace using a graphite crucible. The microstructure of the obtained material was analysed using light microscopy and scanning electron microscopy (SEM). Compression tests were conducted in order to nucleate precipitates under applied stress in the [111]-type direction with the objective of producing a single family of particles, i.e., precipitates with only one orientation relationship with the single crystalline matrix. The evolution of the precipitation process was studied through transmission electron microscopy (TEM) analysis, and the associated stress and temperature dependence of the precipitation kinetics was subsequently evaluated.