Recrystallization behavior of Zr-xNb alloys

The effect of Nb contents on the recrystallization behavior of a binary Zr-xNb was studied. The specimens of Zr-xNb alloys containing 0.2, 0.4, 0.8 and 1.0 mass % Nb were prepared under various heat-treatment conditions for a cold rolled sheet. The recrystallization behavior was evaluated by using a polarized optical microscope, TEM, and a Vickers hardness tester. The recrystallization temperature of the binary alloys was slightly increased with the Nb content. It was caused by an increment of the activation energy due to an increasing Nb content. The grain growth at the high temperature region was decreased with the Nb content, because the fraction of the beta-phase, which is determined by the Nb content, was increased by increasing the Nb content. Because the minimum hardness value was observed in the temperature range between 600 and 700degC, the annealing was performed in this range to obtain a good ductility in a high Nb-containing Zr alloy. (author)