Grain and Microstructure of Cast Mg AZ31-B Alloy Produced by the Magnetic Suspension Melting Process

摘要

Magnesium is the lightest of all structural metals and offers significant weight savingsrncompared to traditional automotive materials. One of the processing difficulties of such arnreactive metal is contamination of the alloy with oxides during melting. This paper describesrnmacro/microstructure of cast Mg AZ31-B alloy using the Magnetic Suspension Melting (MSM)rnat a low superheat of 5℃. Metallographic examination of the MSM cast alloy shows no evidencernof oxide formation. It was also found that casting at this low superheat produce fine cellularrngrain structure compared to the dendritic structure in conventionally cast alloys. Thernintermetallic phases were analyzed in detail and compared with the conventionally cast alloy.rnThe MSM cast ingots at low superheat γMg_(17)AL_(12) phase is formed only at therngrain boundaries in the entrapped aluminum rich secondary- αbetween cellular grains.rnDistribution and morphology of the intermetallic phases found in the MSM and conventionallyrncast AZ31B alloy are presented.