Deformation mechanisms of nil temperature ductile polycrystalline B2 intermetallic compound YAg

Rolf Schaarschuch, Carl-Georg Oertel, Guanghui Cao, Jens Freudenberger, Heinz-Günther Brokmeier, Werner Skrotzki

Index: 10.1016/j.actamat.2018.03.064

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Abstract

The most ductile rare earth intermetallic compound, YAg, was subjected to an thermal activation analysis at low temperatures down to 4 K. Evaluation of the activation parameters and their dependence on stress and temperature yields strong indication for forest dislocation cutting as the rate-controlling deformation mechanism, similar to face-centered cubic metals. Surprisingly, nil temperature ductility was observed. Together with results of a detailed TEM analysis of the active slip systems it is concluded that, despite of violating the von Mises criterion for the plastic deformation of polycrystalline materials, a low elastic anisotropy and/or low Peierls stress is responsible for the appreciable ductility at low temperatures. This finding may help to search for other ductile systems in the broad class of intermetallic compounds.