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

Highlights: • Al–Si–Cu–Mg alloy was modified by introducing Zr, V, and Ti. • The chemistry of the phases was identified using SEM/EDX. • The crystal lattice parameters of the phases were characterized using EBSD. • To investigate the phase stability, XRD was performed up to 600 °C. • Thermal analysis was done to find out the possible phase transformation reactions. - Abstract: 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