Effect of annealing on the microstructure and mechanical properties of high purity erbium metal

Abstract The high purity erbium (Er) with purity ≥ 99.9% was rolled with accumulated deformation of 80%, and the deformed high purity Er was annealed at different temperatures. The microstructure and properties of deformed high purity Er during annealing were studied by means of electron back-scatter diffraction (EBSD) and microhardness tester, respectively. Experimental results showed that after annealing, the deformed microstructure was replaced by fine equiaxed grains. The microstructure and grain orientation distributed were most homogeneously when annealing temperature was 570 °C. And the recrystallization grains component increased with the annealing temperatures increased until 570 °C. After annealing progress, there was a progressive reduction of Low-Angle Grain Boundaries (LAGBs) fraction and a subsequent increase in High-Angle Grain Boundaries (HAGBs). The microhardness of rolled samples was higher than annealed samples, and decreased with increase of the temperatures due to the recovery, recrystallization and grain growth of the Er metal when the annealing temperature less than 570 °C. The microhardness increased a little after annealing at 620 °C. The optimum annealing temperature was 570 °C for high purity Er metal with 80% rolling deformation.