Effects of rare-earth elements Gd and Y on the solid solution strengthening of Mg alloys

A number of Mg-Gd, Mg-Y binary and Mg-Gd-Y ternary alloys are investigated in terms of solid solution strengthening efficiency in this work. It is found that both gadolinium and yttrium in solid solution give a c(n) concentration dependence of the yield strength, where c is the solute atom concentration and n = 1/2 or 2/3. This simplified analysis illustrates that we are able to satisfactorily predict the ternary solid solution strengthening in Mg-Gd-Y alloys. Gd and Y in solid solution are found to give a considerably higher strengthening effect than Al and Zn. It is suggested that, in addition to the classical size and/or modulus misfits model, the valency effect may account for the enhanced strengthening of Gd and Y in Mg. (C) 2009 Elsevier B.V. All rights reserved.