Preparation of large grained Al64Cu23Fe13 icosahedral quasicrystal directly from the melt

Various phase diagrams including an icosahedral (i-) phase in Al-Cu-Fe allo y system were examined in order to reveal the composition of the liquid in equilibrium with the Al64Cu23Fe13 i-phase. The i-phase was formed through t he peritectic reaction between the liquid and the primary lambda(2)-crystal . Prevention of the peritectic reaction was necessary to produce a single q uasicrystal, however, there was a little compositional area of the molten a lloy, which can crystallize the i-phase as a primary crystal. In the conven tional solidification of Al60Cu37Fe3 alloy, almost primary crystalline part icles were classified as i-phase, and the rests were At-phase. The hz-parti cles acted as the inhomogeneous crystallization sites of an i-quasicrystal growth. So, several metallurgical treatments were tried to prevent the lamb da(2)-crystallization. Consequently, we found out an Al59Cu37Fe3Si1 molten alloy, which can crystallize the Al64Cu23Fe13 i-phase as a primary crystal at 978 K. The Al59CU37Fe3Si1 molten alloy should be treated the preliminary cyclic melting process to prevent the lambda(2)-crystallization. And we su cceeded to grow up the large grained Al64Cu23Fe13 i-quasicrystal directly f rom the molten alloy.