Grain growth and phason-strain field in quasicrystalline Al-Li-Cu

We report on grain growth and related structure change in single phased Al- Li-Cu quasicrystals. The icosahedral phase grains have been investigated us ing scanning ion microscopy and transmission electron microscopy. Regular b oundaries between large grains have been observed both before and after hig h temperature annealing. The electron diffraction study shows that the grai n growth is accompanied by a reduction of the phason-strains. The orientati on relation between grains sets the 2-fold icosahedral axes parallel, and t he coincidence of the planes depends on the phason strain-field. The effect of phason-strain field on these boundaries is discussed. It is proposed th at the phason strain elimination can play a role in the grain growth.