Hardness and microstructure of internally oxidized silver alloys

Alloys of Ag, Ag/1.12 at.% Mg, and Ag/0.25 at.% Mg-0.25 At.%Ni were interna lly oxidized at 450 to 825 degrees C and their hardnesses and:microstructur es were observed. Microhardness profiles showed that hardness was high near the surface and decreased with depth into the sample. Microstructures cont ained regions of small and large grains, where region sizes were dependent on treatment temperature. Transitions between small- and large-grained regi ons were abrupt. Treatments at higher temperatures failed to alter grain st ructure, indicating that Mg-O clusters had indeed pinned the grain boundari es. Clustering was shown to affect the hardness of oxidized alloys, not onl y by inhibiting grain growth, but also by inhibiting dislocation motion.