Effects of calcium additions on microstructure and creep behaviour of AE42 alloy
- 19 July 2005
- journal article
- research article
- Published by SAGE Publications in Materials Science and Technology
- Vol. 21 (7) , 847-854
- https://doi.org/10.1179/174328405x41010
Abstract
The as cast microstructure of alloy AE42 is composed of the α-Mg matrix and Al11RE3 compound, which is unstable and decomposes to Al2RE and Mg17Al12 (β) at temperatures above 150°C. A small amount of calcium added to the AE42 alloy results in a significant microstructure refinement and formation of Al2Ca compound, which shows two kinds of morphologies: eutectic lamellar at grain boundaries of the α matrix and tiny lamellar in the matrix grains. With the increase of added calcium the volume fraction of Al2Ca increases, while Al11RE3 decreases in the AE42 alloy. Creep resistance of the alloy is significantly improved with calcium addition. The microstructure of the specimen after creep tests at 175°C and 70 MPa with 2% of calcium addition has no obvious changes compared to that before the creep test, indicating Al2Ca has high thermal stability, which is the key factor in creep resistance improvement.Keywords
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