Temperature dependence of dislocation dissociation mode in L12 trialuminides

Dislocation structure in deformed L12-(Al,Cr)3Ti and L12-Al3Sc alloys were investigated by transmission electron microscopy (TEM). Emphasis was placed on the determination of the mode and temperature dependence of dissociation of superdislocations. Results are as follows: Yield strength versus temperature curve shows a plateau or anomaly in the intermediate temperature range. In (Al,Cr)3Ti, a〈110〉 superdislocations dissociate on a 111 plane into two (a/2)〈110〉 superpartials separated by an APB, up to 923 K. The separation width increases monotonously with increasing temperature. In Al3Sc, a〈110〉 superdislocations dissociate on a 111 plane into two a/3)〈112〉 superpartials separated by a SISF. No considerable change in the separation width is observed up to 783 K.