1.Effects of Ce on the microstructure and mechanical properties ofextruded Mg-Al-Ca alloys

Abstract:

The Mg-Al-Ca alloy has coarse grains and low strength，which makes it difficult to meet the requirements of engineeringstructural components． The effects of Ｒare earth Ce element on the microstructure and mechanical properties of extrudedMg-3Al-1. 8Ca-xCe ( x = 0，0． 2% ，0． 4% ，0． 6% ，mass fraction) alloys were investigated by means of metallographic microscope，scanning electron microscope，X-ray diffraction analysis，Vickers microhardness test and tensile test． The results show that the homoge-nized alloy is composed of α-Mg matrix and reticular Al 2 Ca secondary phase． After adding 0． 60% Ce，the secondary dendrite armspacing decreased by 28． 20% ，and the alloy microstructure was refined． After hot extrusion，the coarse secondary phase was brokeninto particles and distributed in a streamline pattern，which can improve the strength and elongation of the alloy． With the increase ofCe content，the room temperature tensile properties and hardness of the alloy gradually increase． Compared with the alloy without rareearth addition，the tensile strength of the extruded Mg-3Al-1． 8Ca-0． 6Ce alloy increased by 4． 20% ，and the elongation increased by30． 00% ． Its tensile strength，yield strength and elongation were 328． 70 MPa，283． 10 MPa and 8． 60% respectively，and the hard-ness was 73． 70 HV．

Keywords: Mg-Al-Ca alloy; Ce element; hot extrusion; microstructure; mechanical property