抄録
To reveal grain-size dependency and mechanism of creep of 1050 aluminum at low temperatures, creep tests were performed for the samples with grain sizes (d) of 1.0–47 µm at 233–473K. Dislocation creep rate-controlled by non-diffusion process was observed at low temperatures, i.e., T<400K and 280K for coarse (CG) and ultrafine grained (UFG) specimens, respectively. The former showed creep at more than 0.2% proof stress, whereas the latter did it at less than that stress. Creep behavior of UFG aluminum was similar to ambient-temperature creep of hexagonal close-packed metals because apparent activation energy was about 30 kJ/mol. Although grain-size exponent was small, i.e. p=0–0.3, in CG and UFG regions, transient region was observed at d=1.7–10 µm and creep rate decreased of about one order. At high temperatures, CG and UFG aluminum showed conventional dislocation creep rate-controlled by dislocation-core diffusion.
