Effects of Fe addition and addition sequence on carbon inoculation of Mg-3%Al alloy

摘要

The Mg-3%Al melt was treated by carbon inoculation and/or Fe addition. The effects of Fe addition and addition sequence on the carbon inoculation of Mg-3%AI alloy were investigated in the present study. The role of Fe in the grain refinement of Mg-3%Al alloy treated by carbon inoculation was closely associated with the operating sequence of carbon inoculation and Fe addition. Fe has no obvious effect on the grain refinement of Mg-3%Al alloy by carbon inoculation under the condition that Fe pre-existed in the Mg-3%Al melt before carbon inoculation. However, Fe played an inhibiting role under the condition that the Mg-3%Al melt had been inoculated by carbon before Fe addition. The Al-C-O particles were observed in the sample treated only by carbon inoculation. In addition to Al-C-O particles, Al-C-O-Fe particles could be observed in the sample treated by Fe addition and then carbon inoculation. These Al-C-O and Al-C-O-Fe particles, actually being Al-C and Al-C-Fe phases, should be the potent nucleating substrates for Mg grains, resulting in the grain refinement. However, the Al-C-O-Fe-rich intermetallic particles were mainly observed in the samples treated by carbon inoculation and then Fe addition. The Al-C-O-Fe particles, actually being Al-C-Fe phases, formed under this condition should not be the potent nucleating substrates for Mg grains, resulting in the grain coarsening.