Microstructure and mechanical properties of Mg-Al-Ca-Nd alloys fabricated by gravity casting and extrusion process

Abstract

The as-cast microstructure of Mg-5Al-3Ca-xNd alloys consists of equiaxed a-Mg matrix, (Mg, Al)2Ca eutectic phase and Al-Nd rich intermetallic compounds. With the increase of Nd addition, a-Mg matrix morphology was changed from dendritic to equiaxed grains due to suppression of grain growth by formation of homogeneous intermetallic compounds containing Nd dispersed at grain boundary and a-Mg matrix. And the grain size of as-cast alloys was decreased as addition of Nd was increased. This eutectic phase of the extruded alloys was elongated to extrusion direction and size of this phase was redined comparing to that of as-cast alloys because of severe deformation during hot extrusion. Maximum yield and ultimate tensile strength value of the as-extruded alloys was 322 and 335 MPa at Mg-5Al-3Ca-2Nd alloy, respectively. © 2008 The Japan Institute of Metals.