Thermo-mechanical processing, microstructure and mechanical properties of TiZrB alloy

This work was aimed in the relationships investigation among the microstructure, the tensile properties and the thermo-mechanical processing of a novel Ti-25Zr-1B (wt%) alloy. The alloy was evaluated under different conditions (as-cast, hot-rolled and hot-rolled-annealed). The XRD diagrams demonstrated that all specimens were completely consisted of the alpha and TiB phases. The results of EDS indicated that the TiB phase dissolved a certain amount of Zr, which was in agreement with the existence of TiB peaks shifting towards lower diffraction angles. The as-cast Ti-25Zr-1B alloy microstructure and the size, the morphology, the orientation, and the distribution of the TiB particles could be significantly altered by the hot-rolling process. The hot-rolling process provided an ultimate strength increase of at least 7 pct and the elongation-to-failure increase of 135 pct relatively to the as-cast sample. In addition, the annealing heat treatment could effectively modify the mechanical properties of the hot-rolled sample. The strength decreased and the elongation-to-failure increased as the annealing temperature increased, while the temperature was below 800 degrees C. In contrast, as the annealing temperature increased to 900 degrees C, the alloy demonstrated appreciably lower elongation-to-failure and higher strength compared to the annealed form at 800 degrees C. The mechanical properties variation of the Ti-25Zr-1B alloy series was ascribed to the microstructure evolution of the matrix alloy as well as to the morphology and volume fraction changes of the TiB particles.