Ultra-fine grain size and isotropic very high strength by direct extrusion of chill-cast Mg-Zn-Y alloys containing quasicrystal phase

Very fine grain sizes up to similar to 1 mu m with yield strengths up to about 400 MPa in tension and compression, with elongations ranging from 12% to 18%, have been achieved by chill casting and direct extrusion of Mg(93)Zn(6)Y alloy containing a quasicrystalline phase. These alloys respond to ageing at 150 degrees C, showing two peaks. The hardness stabilizes at the level of the second peak. The effect of precipitation on the yield strength, ductility and yield asymmetry has been studied. (C) 2010 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.