On the abnormal negative temperature dependence of yield strength in the L1₂ compound Fe₃Ge

Abstract

Both the as-annealed and room temperature deformed microstructure of the L1₂ compound Fe₃Ge have been studied using transmission electron microscopy. The as-annealed microstructure consisted of a dense array of stacking faults on {111} planes and a small concentration of thermal APB's on {100} planes. In the deformed microstructure, <110>{001} cube slip has been identified. The asannealed stacking faults may also produce a strengthening effect on such slip. A combination of these two factors causes the large and negative temperature dependence of yield strength in Fe₃Ge. The absence of octahedral slip is attributed to the fact that there is no dislocation configuration on {111} planes which is both glissile and allowed energetically.