TEMPERATURE EFFECT ON FORMATION OF REORIENTATION BANDS IN ALPHA-TI

The temperature dependence of the critical deformation epsilon(cr) ini tiating dislocation reorientation bands (RBs) in alpha-Ti polycrystals of commercial purity is obtained by the method of statistical process ing of TEM (transmission electron microscopy) images. A dependence of the specific volume beta occupied by the RBs in the polycrystal upon t he strain epsilon and the temperature (4.2-393 K) is found. The effect s observed are attributed to a decrease in the relative mobility of sc rew dislocations (as compared with edge dislocations) upon lowering th e temperature,the thermally activated nature of dislocation rearrangem ents in the process of RB formation and the character of the temperatu re dependence of the critical shear stresses of slip and twinning. (C) 1998 Elsevier Science S.A. All rights reserved.