DISSOCIATION OF 1/3[(1)OVER-BAR(1)OVER-BAR26](11(2)OVER-BAR1) SUPERDISLOCATIONS IN T1(3)AL SINGLE-CRYSTALS DEFORMED AT HIGH-TEMPERATURES

The dissociation of 1/3[($) over bar 1 ($) over bar 126]{11 ($) over bar 21} superdislocations was studied with transmission electron microscopy in Ti(3)A1 single crystals deformed at high temperatures where the yield stress increased with increasing temperature, attaining a maximum stress at about 700 degrees C. Near the peak-stress temperature all the dislocations observed were pairs of unlike 1/6[($) over bar 1 ($) over bar 126] superpartials loosely bound by an antiphase boundary ribbon about 300 nm wide on {11 ($) over bar 21} plane. At much higher temperatures, e.g. 900 degrees C, 1/6[($) over bar 1 ($) over bar 126] superpartials tend to decompose to [0001] and 1/6[($) over bar 1 ($) over bar 120] dislocations.