Theoretical and Experimental Study of the Al – Cu – Si – Sn Phase Diagram in the Range of Aluminum Alloys

Phase compositions of aluminum alloys of the Al – Cu – Si – Sn system are studied by computational and experimental methods. The computations are performed with the use of the Thermo-Calc software; the experimental part is implemented with the use of light and scanning electron microscopy, microscopic x-ray spectrum and thermal analyses. According to the computation, the quaternary system may exhibit layering of liquid and occurrence of monotectic transformations including a five-phase nonvariant one. The solidus temperature of the quaternary alloys depends little on the presence of copper and silicon and virtually coincides with the melting temperature of pure tin. The solubility of tin in the aluminum solid solution and in the (Si) and Al₂Cu phases is negligibly low. Heating at 500°C changes substantially the morphology of the tin phase.