Effect of Modification on Microstructure and Properties of AZ91 Magnesium Alloy

• Main Authors: Andrzej Kiełbus, Robert Jarosz, Adam Gryc
• Format: Article
• Language: English
• Published: MDPI AG 2020-06-01
• Series: Crystals
• Subjects: grain refinement; AZ91; overheating; hexachloroethane; wax-CaF₂-carbon; microstructure
• Online Access: https://www.mdpi.com/2073-4352/10/6/536

Refinement of α-Mg solid solution grains has a significant influence on the improvement of mechanical properties of cast magnesium alloys. In the article, the effects of three modifiers on microstructure and properties of AZ91 magnesium alloy casted to a sand mould were described. Overheating, hexachloroethane and wax-CaF₂-carbon powder were applied. The research procedure comprised microstructure analysis by means of light microscopy, scanning electron microscopy and quantitative analysis with <i>AnalySIS Pro^®</i> software and mechanical properties’ investigation. The microstructure of AZ91 alloy in the as-cast condition consists of α-Mg solid solution with precipitates of Mg₁₇Al_12, Mg₂Si and Al₈Mn₅ phases. It was reported that all applied modifiers cause refinement of α-Mg solid solution grains and a decrease of the volume fraction of α-Mg+Mg₁₇Al₁₂ compound discontinuous precipitates. The best results were obtained in the case of wax-CaF₂-carbon powder.