Effects of combined addition of Y and Ca on microstructure and mechanical properties of die casting AZ91 alloy

• Published in: Transactions of Nonferrous Metals Society of China Vol. 20; no. B07; pp. 311 - 317
• Main Author: 王峰 王越 毛萍丽 于宝义 郭全英
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.07.2010; School of Materials Science and Engineering,Shenyang University of Technology,Shenyang 110023,China
• Subjects: Alloy development; Alloy systems; Alloying additive; AZ91Mg alloy; AZ91合金; calcium; Casting alloys; Die casting; die casting magnesium alloy; Magnesium base alloys; Mechanical properties; Microstructure; tensile property; yttrium; 力学性能; 微合金化; 扫描电子显微镜; 钙结合; 镁合金压铸件; AZ91Mg alloy; calcium; microstructure; yttrium; die casting magnesium alloy; tensile property
• ISSN: 1003-6326
• DOI: 10.1016/S1003-6326(10)60489-X

A series of die casting heat-resistant magnesium alloys based on Mg-Al system were developed for automotive application by adding Y and various amounts of Ca. The mechanical properties and microstructures of die casting AZ91 alloy with combined addition of Y and Ca were investigated by optical microscopy, scanning electronic microscopy, X-ray diffractometry and mechanical property test. The results show that the combined addition of Y and Ca can refine the as-die-cast microstructure, result in the formation of Al2Ca phase and Al2Y phase, and inhibit the precipitation of Mg17Al12 phase. The combined addition of Y and small amount of Ca has little influence on the ambient temperature tensile properties, but increasing the content of Ca can improve significantly the tensile strength at both ambient and elevated temperatures. It is found that for AZ91-1Y-xCa alloy, the hardness and the elevated temperature tensile strength increase, while the elongation decreases with increasing the addition of Ca. The mechanism of mechanical properties improvement caused by the combined addition of Y and Ca was also discussed.