A numerical Newtonian thermal analysis (NTA) method was carried out for online monitoring the solidification course of commercial Al-Si alloys. The solidification paths of different molten Al-Si alloys were characterized by the fraction solid curves. The variation of heat capacity of Al and Si were concerned in the determination of baseline evaluation of latent heat. In this experiment, the commercial pure Al, Al-1Si, Al-5Si, Al- 9Si, Al-13Si and Al-18Si alloys were molten at 800 ℃ and cooled at room temperature, respectively. The cooling curves of these alloys were measured by suing a K-type thermocouples. The liquidus temperatures of these alloys decreased with the increase of Si %. An obvious stage occurred at about 580 ℃ was related to Al-Si eutectic reaction. The phase fraction difference of these alloys were supported by the microstructure observation.
