Dislocation structures of β-CuZn deformed in compression between 25 and 300°C

Dislocation structures of β-CuZn single crystals with two different orientations deformed in compression between room temperature and 300°C, where the anomalous strength peak occurs, have been examined by the high-order reflection imaging technique in a HVEM; Burgers vectors of the dislocations have been determined without ambiguity by the g·b = 0 invisibility criterion. In crystals deformed below T p (the temperature at which the strength shows the peak in the stress versus temperature curve), <111> superlattice dislocations, consisting of two 1/2<111> superpartials, are predominant, while in crystals deformed at or above T p, <010> and <101> dislocations are predominant. Mechanisms so far proposed to explain the anomalous strength peak are criticized on the basis of the present observations.