Loss in coherency and coarsening behavior of Al3Sc precipitates

Abstract The coarsening behavior of the Al 3 Sc particles in Al–0.2wt%Sc alloy at 673–763 K is studied on the basis of TEM observations with the numerical model. Emphasis is on the effects of coherent/semi-coherent transition of the particles. The radius for coherent/semi-coherent transition of the Al 3 Sc particles is determined from TEM micrographs as 15–40 nm. The average particle radius, r ave , of the Al 3 Sc particles obeys the r ave 3 growth low both in the coherent stage ( r ave r ave >40 nm). However, in the intermediate stage, where coherent and semi-coherent particles coexist (15 r ave