Effects of calcium additions on microstructure and creep behaviour of AE42 alloy

Abstract

The as cast microstructure of alloy AE42 is composed of the a-Mg matrix and Al 11 RE 3 compound, which is unstable and decomposes to Al 2 RE and Mg 17 Al 12 (b) at temperatures above 150uC. A small amount of calcium added to the AE42 alloy results in a significant microstructure refinement and formation of Al 2 Ca compound, which shows two kinds of morphologies: eutectic lamellar at grain boundaries of the a matrix and tiny lamellar in the matrix grains. With the increase of added calcium the volume fraction of Al 2 Ca increases, while Al 11 RE 3 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 175uC and 70 MPa with 2% of calcium addition has no obvious changes compared to that before the creep test, indicating Al 2 Ca has high thermal stability, which is the key factor in creep resistance improvement.

Effect of Ca and Sr additions on high temperature and corrosion properties of Mg–4Al–2Sn based alloys

“…These alloys offer an excellent combination of mechanical properties and corrosion resistance. However, these alloys have poor creep resistance at temperatures above 120 • C, which make them unsuitable for major power train applications, whose service temperature is approximately 200 • C. An attempt was made to improve the creep resistance of the existing Mg-Al based alloy by introducing thermally stable intermetallics through the addition of different alloying elements and thereby improving its elevated temperature performance [5][6][7][8]. Mg-Al-Sr alloys [9] are quite effective and are currently used in BMW engine blocks.…”

Effects of Nd on microstructure and mechanical properties of as-cast LA141 alloys

“…Most commonly used alloying elements are Al, Zn, Zr, RE, etc. Many researchers have studied Mg-Al, Mg-Zn, Mg-Ca alloys [8][9][10][11]. Research results show that, RE in these alloys has many favorable effects such as melt purification, microstructure improvement, grain refinement, and dispersion strengthen.…”

Effect of Al contents on microstructures, tensile and creep properties of Mg–Al–Sr–Ca alloy

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