The ability of cast composite technology to enhance ductility of wrought magnesium and alloys

Abstract

At ambient temperature, hexagonal close packed magnesium has limited ductility due to low availability of active slip systems. In this work, 3 methods of enhancing the ductility of wrought magnesium are discussed, namely: (1) addition of microparticles such as Ti, Mo and SiC (Method 1), (2) addition of various oxide nanoparticles as well as carbon nanotubes (Method 2) and (3) use of aluminium based core as continuous reinforcement (Method 3). In Method 1, the magnesium matrix is softened (Ti microparticle case), delo-calized in deformation (Mo microparticle case) or in a reduced state of stress around the microparticle after heat treatment (SiC microparticle case). In Methods 2 and 3, the basal plane in magnesium is sometimes tilted from 0° to 45° (to the force axis), enabling basal slip to occur more easily in the composite. In the cases where the basal plane is oriented parallel to the force axis, non-basal slip at room temperature occurs more easily between the aligned basal planes. In Method 2, the nanoparticles present also provide sites where cleavage cracks are opened ahead of the advancing crack front. An attempt is made to correlate the ductility enhancement of wrought magnesium as a function of the way it is reinforced. © Carl Hanser Verlag GmbH & Co. KG.