IMPROVING THE AL6LI3CU QUASI-CRYSTALS BY ANNEALING TREATMENTS

The Al6Li3Cu (T2) phase is known as a very imperfect icosahedral quasi crystal. Up to now, the cast phase has not been annealed because of th e difficulties in preventing lithium loss during annealing. By using a dedicated device described in the present paper, it has been possible to carry out thermal treatments at temperatures higher than 500 degre es C. The procedure involves two steps: the former aims at eliminating the eutectic phases; the latter is a long annealing at 575 degrees C that improves the quasicrystal structure. The quality of the annealed quasicrystals was checked by transmission electron microscopy investig ations. A comparison of several specimens of annealed Al6Li3Cu (T2) ph ase with the cast material is reported.