Solidification behaviour of Al–Si based alloys with controlled additions of Eu and P

Abstract

The solidification behaviour of Al–Si based alloys with controlled additions of Eu (up to 200 ppm) and P (up to 10 ppm) was investigated using thermal analysis in a conventional die casting condition. The results indicate that P may be removed or involved into the formation of EuP phase. Furthermore, the formation of EuP phase appears to have a beneficial effect on the nucleation of Si and thereby the refinement of eutectic grains. A simultaneous modification of the eutectic Si and refinement of the eutectic grains was achieved by a combined addition of Eu and P, which is believed to be of extremely importance to optimize the number, size and size distribution of casting defects. The observation and analysis of pores using computed tomography strongly supports this argument. The obtained results in the present investigation can, therefore, give some novel insights in controlling the solidification microstructure of Al–Si based alloys.