Experimental isothermal sections of the ternary phase diagram Al–Cu–Si at 600 °C and 800 °C

Abstract

The phase diagram of the Al–Cu–Si ternary system was investigated experimentally at the temperatures 600 °C and 800 °C. The current study was designed to contribute to a better understanding of the ternary phase diagram Al–Cu–Si at elevated temperatures, where some of the phase equilibria were only tentatively known. It was found that the ternary phase τ proposed earlier is actually an extended solid solution of Al in the CuSi_δ phase. At 700 °C, the phase CuSi_δ is stable as a pseudo ternary phase, and the existence of a significantly extended thermal stability range in the ternary was also confirmed by DSC measurements. In agreement with previous isothermal sections at other temperatures, a huge solubility of aluminum in CuSi_κ and negligible solubility of Si in AlCu_β was observed.