Saturation phenomenon of Ce and Ti in the modification of Al-Zn-Si filler metal

Cerium and titanium were added to an Al-42Zn-6.5Si brazing alloy, and the subsequent microstructures of the brazing alloy and the 6061 Al alloy brazing seam were investigated. The microstructures of filler metals and brazed joints were characterized by scanning electron microscopy and X-ray energy dispersion spectrometry. A new Ce-Ti phase formed around the silicon phase in the modified filler metal and this saturation phenomenon was analyzed. Interestingly, following brazing of the 6061 alloy, there is no evidence of the Ce-Ti phase in the brazing seam. Because of the mutual solubility of the brazing alloy and base metal, the quantity of the solvent increases, and the solute Ce and Ti atoms assume an undersaturated state.