X-ray diffraction studies of grain growth in an ultra-fine grained 6060 aluminium alloy

摘要

In-situ synchrotron X-ray diffraction has been applied in order to study grain growth in an ultra-fine grained (D～400 nm) 6060 aluminium alloy at 270°C. The submicron grain structure was produced by Equal Channel Angular Pressing (ECAP) to an effective strain of ～6 without rotation of the billet. As the material was textured after ECAP, the initial stages of grain growth were seldom detected, but in the grain size interval available for studies a grain growth exponent of 3.6±0.3 was obtained. By interpolation of the grain growth curves to D=D_0 (determined by EBSD) the effect of growth on the softening of the alloy was estimated. The interpolated average curve indicates that the initial stages of softening are not due to uniform grain growth, but rather reconfiguration and annihilation of dislocations as well as overaging of hardening precipitates.