Effect of low frequency vibration on porosity of LM25 and LM6 alloys

This study summarises research into the effect of low frequency mechanical vibration on the porosity of unmodified and metallic sodium modified LM25 [Al–Si 7.15%] and LM6 [Al–Si 12.30%] alloys. Vibration at varying frequencies between 15 and 41.7 Hz and amplitudes between 0.125 and 0.5 mm has been applied to both unmodified and metallic sodium modified LM6 and LM25 alloys during solidification. The effect of low frequency vibration on the porosity was analysed using optic and quantitative metallographic techniques. The results indicated that: (1) LM25 and LM6 alloys grain refined with Nucleant2 reduced the pore volume %. (2) The amount and size of pores were increased with increasing vibration intensity in unmodified LM25 and LM6 alloys. (3) The modification with metallic sodium in LM25 and LM6 alloys produced fewer but larger pores than found in unmodified alloys in the static condition. (4) Vibration of sodium modified LM25 and LM6 alloys increased the amount and size of the pores. (5) Vibration at frequencies of 31.7–41.7 Hz and amplitudes of 0.375–0.5 mm produced large holes on the top of the ingot in unmodified and modified LM25 and LM6 alloys.