Inoculant Fading-Resistance of Fe-Bearing Mg–3%Al Alloys Refined by Carbon Combining with Calcium Addition

Abstract

Mg–3%Al alloys containing different trace Fe contents were treated by carbon combining with Ca inoculation. The holding time after being inoculation was adjusted from 5 to 80 min. The effect of holding time on grain refinement and the structures of nucleating particles were systematically investigated. Significant grain refinement is obtained for the Mg–3%Al alloys containing trace Fe refined by carbon combining with Ca inoculation. The grain size keep stable with prolonging the holding time and exhibit significant fading-resistance. The duplex-phase particles of Al–Fe coated with Al–C-rich phase could be easily observed and they should actually act as potent nuclei for Mg grains. The Ca content in the Al–C-rich shell is obviously higher than that in the Mg matrix. The segregation of Ca on the surfaces of different phases contributes to the formation of duplex-phase particles and keeps the duplex phase structure particles stable. Consequently, no inoculant-fading of carbon-inoculation occurred due to the high stability of the duplex phase structure particles.