Effect of holding time on microstructure of Mg-9Al-1Si alloy during semisolid isothermal heat treatment

• Published in: Transactions of Nonferrous Metals Society of China Vol. 20; no. B07; pp. 430 - 434
• Main Author: 马国睿 李新林 李庆芬
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.07.2010; Center for Biomedical Materials and Engineering,College of Materials Science and Chemical Engineering,Harbin Engineering University,Harbin 150001,China
• Subjects: Heat treatment; Intermetallic compounds; Intermetallics; isothermal heat treatment; Magnesium base alloys; Magnesium compounds; Mg 2Si phase; Mg2Si; Microstructure; modification; Semi-solid; Semi-solid processing; Semiconductors; Silicides; 保温时间; 半固态浆料; 合金; 形状变化; 热处理过程; 等温处理; 非枝晶组织; isothermal heat treatment; Mg 2Si phase; Semi-solid; modification; Mg2Si phase
• ISSN: 1003-6326
• DOI: 10.1016/S1003-6326(10)60512-2

The effects of isothermal holding time on the semisolid microstructure of Mg-9Al-1Si（mass fraction,%）alloy were investigated.The research results indicate that the Mg-9Al-1Si alloy with non-dendritic microstructure can be produced by the semi-solid isothermal heat treatment.With holding time varying from 5 to 30 min,the volume fraction of liquid is gradually enlarged from 29.3%to 38.6%,the morphology ofα-Mg grains changes from initial dendritic shape to spherical types and their average sizes increases from 41.1 to 56.1μm.In addition,during the isothermal heat treatment,the eutectic Mg2Si phase changes from the initial Chinese script shape to granule and/or polygon shape in Mg-9Al-1Si alloy.The modification of Mg2Si phase is possibly attributed to a shift of the eutectic composition of the liquid in semi-solid slurries,towards lower silicon contents with increasing Al content due to a redistribution of Al during isothermal heat treatment.