The influence of strontium addition on the microstructure of a Mg-9Al-2Ca alloy was investigated. The microstructure of Mg-9Al-2Ca-xSr alloys consists of α-Mg, (Mg,Al)2Ca with C15 structure, Al4Sr and AlxMny phases. The addition of strontium decreases the grain size of the α-Mg phase and decreases the aluminum content dissolved in the α-Mg solid solution. Moreover, the volume fraction of the Al4Sr phase increases with increasing strontium content. Strontium does not influence on the volume fraction of (Mg,Al)2Ca phase.
Abstract
The structure of Mg-9Al-2Ca-xSr alloys is composed of a-Mg grains and the Al2Ca and Al4 Sr phases in the interdendritic areas. These phases are formed as a result of eutectic reactions. Globular particles of the Al8Mn5 phase are observed within the interior of the grains. The addition of strontium to Mg-9Al-2Ca-0.4Mn alloys causes the formation of the Al4Sr phase and increase of its volume fraction with increasing strontium levels. Moreover, increase of the strontium amount causes a decrease of aluminum content in the a-Mg solid solution.
The Influence of Strontium on the Microstructure of Cast Magnesium Alloys Containing Aluminum and Calcium