Formation, characteristics and control of sludge in Al-containing magnesium alloys: An overview

• Published in: Journal of magnesium and alloys 2022-03, Vol.10 (3), p.599-613
• Main Authors: Fu, Y., Wang, G.G., Hu, A., Li, Y., Thacker, K.B., Weiler, J.P., Hu, H.
• Format: Article
• Language: English
• Subjects: Al-Mn(-Fe) intermetallics; Die casting; Magnesium alloys; Magnesium oxide; Microstructure characterization; Sludge
• ISSN: 2213-9567; 2213-9567
• DOI: 10.1016/j.jma.2021.11.031

Sludge consisting of heavy element phases and oxides is often generated during the casting operation of aluminum (Al) and magnesium (Mg) alloys. With the help of the well-established Sludge Factor (SF) formula, it is relatively easy to control the sludge generation in aluminum alloys. But formation mechanisms and characteristics of sludge in die casting magnesium alloys are still unclear. To ensure the production of high quality die cast components at a low cost, a full understanding of sludge in die casting Mg alloys and its proper control measures need to be developed, since excessive sludge formation affects deleteriously material and operation cost, and casting performance. In the present report, the formation, characteristics and control of Mg die-casting sludge, based on the established knowledge of sludge formation and sludge factor in Al die casting alloys, are reviewed. Previous work on characterization and assessment of sludge in die cast Mg alloys are reviewed. Metallurgical principles for control of sludge in ingot production in association with die casting of Mg alloys are discussed. Rapid assessment of Mg oxide and intermetallics relevant to sludge formation in Mg alloys are highlighted.