Growth and characterization of Al-Cu-Li quasicrystals.
01 January 1988
The alloy system Al-Li-Cu was investigated extensively over the composition range 5.8-8 Al-Cu-3Li to develop a detailed understanding of the formation and properties of the icosahedral phase, known as T sub 2. Material from the various charges was analyzed by optical and electron microscopy, energy dispersive X-ray analysis, differential thermal analysis and differential scanning calorimetry. The role of the melt composition and the solidification velocity were found to be crucial in determining the micro- and macro-structure, and the existence of the icosahedral phase. A partial T-X phase diagram for the region around Al sub 6 CuLi sub 3 is presented based on these analyses. Based on this phase diagram the largest single icosahedral crystals of Al sub (5.1) CuLi sub 3 yet reported, with diameters greater than 1 cm, were produced by Bridgman, methods.