EFFECT OF NANO-SCALE DISPERSION PARTICLES ON THERMAL STABILITY AND CREEP IN BULK CRYOMILLED ULTRAFINE GRAINED 5083 Al

摘要

The preparation of ultra fine grained (UFG) 5083 Al using gas atomization followed by cryomilling leads to introducing oxides (resulting from the breakup of oxide layers that are formed around metal particles during gas atomization), and carbides, nitrides, and other impurities during cryomilling. The results of research in progress show that the presence of these nano- scale dispersion particles affects the behavior of the alloy in several ways. First, the particles enhance thermal stability by suppressing grain growth. Second, they serve as strong obstacles to the movement of dislocations, a process that provides a possible source for a threshold stress during superplastic flow. Finally, they act as sites for cavity nucleation, leading to a loss in ductility.