ON THE LOW STRESS CREEP IN CU-14AL ALLOY AND ALPHA-ZIRCONIUM AT INTERMEDIATE TEMPERATURES

It is shown that during creep in a Cu-14Al solid solution alloy at low stresses and intermediate temperatures, two flow processes act in parallel: (i) stress-directed diffusional transport of matter via the grain boundaries and (ii) grain boundary sliding accommodated by slip in thin zones adjoining the sliding boundaries. However, creep in alpha-zirconium at low stresses and intermediate temperatures results from stress-directed diffusional transport of matter via the grain boundaries up to an intercept grain size of 120-mu-m, while for intercept grain sizes above this value, Harper-Dorn creep operates. An interpretation of the results of the investigations of creep in alpha-zirconium by Bernstein, Fiala and Cadek in terms of grain boundary sliding accommodated by slip as proposed by Ruano, Wadsworth and Sherby is shown to be incorrect.