Improved tensile creep properties of yttrium- and lanthanum-doped alumina:a solid solution effect

The tensile creep behavior of yttrium- and lanthanum-doped alumina (at dopa nt levels below the solubility limit) was examined. Both compositions (100 ppm yttrium. 100 ppm lanthanum) exhibited a uniform microstructure consisti ng of fine, equiaxed grains. The creep resistance of both doped aluminas wa s enhanced, compared with undoped alumina, by about two orders of magnitude , which was almost the same degree of improvement as for materials with hig her dopant levels (in excess of the solubility limit). In addition, measure d creep rupture curves exhibited predominantly steady-state creep behavior. Our results, therefore, verified that the creep improvement in these rare- earth doped aluminas was primarily a solid-solution effect.