Al-Cu-Mg-Zr (Aluminum-Copper-Magnesium-Zirconium)

Lower Order Systems Quaternary Phase Equilibria - For brief descriptions of the binary systems, see [Massalski2]. The binary compounds CuAl2 (C16-type tetragonal, denoted h) and ZrAl3 (D023-type tetragonal) are present in the Al-rich alloys investigated by [2011Rok]. Four ternary phases, besides Laves phase modifications, are known in the Al-Cu-Mg system, see [2007Rag] for an update. Among these, CuMgAl2 (BRe3-type orthorhombic, denoted S) appears in the Al-rich quaternary alloys [2011Rok]. There are ten ternary phases in the Al-Cu-Zr system [2011Rag], but none of them were found in the quaternary alloys of [2011Rok]. The experimental data on the Al-Mg-Zr system were compiled by [1995Vil]. No ternary phases are known in this system. With starting metals of 99.99% Al, 99.96% Cu, 99.96% Mg and 99.8% Zr, [2011Rok] melted quaternary alloys in a resistance furnace, using prior-made Al-Cu and Al-Zr master alloys and a flux covering to prevent Mg evaporation. The alloys were given a final anneal at 490 C for 15 h and quenched in water. The phase equilibria were studied with optical microscopy, x-ray powder diffraction and electron probe microanalysis. The measured compositions of the co-existing phases were listed for one ternary alloy and two quaternary alloys. The isothermal section constructed by [2011Rok] at 490 C and at 0.3 mass% Zr in the Al-rich region is shown in Fig. 1. The binary compounds CuAl2 (h) and ZrAl3 and the ternary phase CuMgAl2 (S) are present. The component concentrations in the compounds Fig. 1 Al-Cu-Mg-Zr isothermal section in the Al-rich region at 490 C and at 0.3 mass% Zr [2011Rok] were near stoichiometric values, with no solubility of other components. A four-phase field of (Al) + h + S + ZrAl3 is seen in Fig. 1. (...truncated)