Effect of Individual Alloying Addition on the Microstructure and Creep Behavior of Squeeze Cast AZ91 Magnesium Alloy

The microstructure of AZ91 (Mg-Al) alloy is comprised of α-Mg and β-Mg 17 Al 12 massive phase. The lower melting point associated with the β-Mg 17 Al 12 phase results in poor creep resistance of the alloy. In the present study, the AZ91 alloy with the addition of calcium (Ca, 1wt%) and cerium (Ce, 1wt%) is cast, and their effect on the microstructure and creep behavior of AZ91 alloy have been investigated. Thermally stable phases such as Al 2 Ca and Al 11 Ce 3 are introduced in the AZ91 alloy through the addition of Ca and Ce elements. Energy dispersive spectroscopy (EDS) and x-ray diffraction analysis confirmed the presence of these intermetallic phases in the microstructure. Tensile creep tests on the as-cast samples were performed at 175 ° C temperature under 50 MPa stress. The study shows that the creep resistance of AZ91 alloy is greatly improved with the presence of Al 2 Ca and Al 11 Ce 3 intermetallic phases because of their better thermal stability than β-Mg 17 Al 12.