Thermal stability of (AlSi)x(ZrVTi) intermetallic phases in the Al-Si-Cu-Mg cast alloy with additions of Ti, V, and Zr

The Al-Si-Cu-Mg cast alloy was modified with additions of Ti-V-Zr to improve the thermal stability of intermetallics at increased temperatures. A combination of electron microscopy, electron backscatter diffraction, and high temperature X-ray diffraction was explored to identify phases and temperatures of their thermal stability. The micro-additions of transition metals led to formation of several (AlSi)x(TiVZr) phases with D022/D023 tetragonal crystal structure and different lattice parameters. While Cu and Mg rich phases along with the eutectic Si dissolved at temperatures from 300 to 500 °C, the (AlSi)x(TiVZr) phases were stable up to 696-705 °C which is the beneficial to enhance the high temperature properties. Findings of this study are useful for selecting temperatures during melting and heat treatment of Al-Si alloys with additions of transition metals.