ON THE ABNORMAL NEGATIVE TEMPERATURE-DEPENDENCE OF YIELD STRENGTH IN THE L12 COMPOUND FE3GE

Both the as-annealed and room temperature deformed microstructure of the Ll2 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 as-annealed 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.