ON GRAIN-BOUNDARY FACETING UNDER STRESS DURING HIGH-TEMPERATURE DEFORMATION OF AL AND AL-GA ALLOYS

Aluminuim of high purity and aluminium with 50 ppm gallium were deform ed under various strain rates and temperatures in order to investigate the possible influence of liquid like grain boundaries on grain bound ary sliding and macroscopic deformation behaviour. Under all condition s, serrated grain boundaries were observed to develop during the tensi le test. Those serrated structures were correlated to the development of subgrains observed by optical metallography and transmission electr on microscopy. In the absence of an applied stress, further annealing lead to disappearing of the serrated grain boundaries when the anneali ng temperature was higher than the tensile test temperature under whic h the serrations were developed. (C) 1997 Elsevier Science S.A.