Abstract:The AlSi20/8009 aluminum alloy was heated to high temperatures near the melting point and cooled to investigate the effect of external Si addition on the phase evolution of Al₁₂(Fe,V)₃Si dispersion. Differential scanning calorimeter, scanning electron microscope, energy dispersive spectrometer and X-ray diffractometer were employed. The results showed that Al₁₂(Fe,V)₃Si and Si phases evolved into a needle-like Al_4.5FeSi phase and a nano-sized V-rich phase during holding the alloy at 580-600 °C. With increasing holding temperature to 620-640 °C, Al_4.5FeSi and nano-sized V-rich phases evolved reversibly into Al₁₂(Fe,V)₃Si and Si phases, of which Al₁₂(Fe,V)₃Si occupied a coarse and hexagonal morphology. During the alloy (after holding at 640 °C) furnace cooling to 570 °C or lower, Si and Al₁₂(Fe,V)₃Si phases evolved into strip-like Al_4.5FeSi and the V-rich phases, which is a novel formation route for Al_4.5FeSi phase different from Al-Fe-Si ternary system.

Key words: SiC_p/8009Al composite; phase evolution; metallurgical joining; re-melting; cooling