DYNAMIC AND STATIC STRAIN-AGING EFFECTS IN FE-MODIFIED L1-2 AL3TI

Serrations have been observed in the stress-strain curves of Fe-modifi ed L1(2) Al3Ti-based alloys at intermediate temperatures and related t o dynamic interactions between mobile dislocations and solute atoms, i .e. dynamic strain aging effects. Serrations appear only at intermedia te, not at high or low temperatures, because of the following reasons: at high temperatures the diffusivity of the solute atoms is high enou gh that the solute atoms and dislocations move together, thereby requi ring no break-away of the dislocations. At low temperatures the diffus ivity of the solute atoms is so low that no dynamic interaction can oc cur, but a static interaction is observed, instead. Thus the entire ra nge of yielding phenomena can be consistently explained in terms of in teractions between solute atoms and mobile dislocations and requires n o assumptions about changes in the nature of dislocation cores. The so lutes giving rise to this effect are likely of substitutional type but have not been identified.