Investigations on deformation mechanism of monocrystalline B2 rare-earth intermetallic compounds at low temperatures

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Tensile test are performed on monocrystalline B2 rare-earth intermetallic compounds (YCu, YAg) of different orientations in the temperature range between 296K and 4K in order to specify the deformation mechanism. Activation parameters are determined by means of stress relaxation experiments and strain-rate-change experiments at several temperatures. On the one hand there is the unique opportunity to study the influence of a second phase (B27-structure) on the deformation mechanism to contribute to the understanding of the brittle-to-ductile transition of YCu. On the other hand the deformation mechanism of YAg can be investigated in a large temperature range and possible changes of mechanism can be detected. By comparing conclusions about the causes of exceptionally high ductility of these B2 intermetallic compounds can be drawn. The goal is a better understanding of the low brittle-to-ductile transition of B2 rare-earth intermetallic compounds.