Effects Of Zr Additions On Microstructures And Elastic Properties Of Ti-25Nb Alloys

In this paper, the Ti-Zr-Nb alloys were prepared using non-consumable arc melting furnace, and then processed by hot-forging, normalizing treatment, cold-rolling and annealing. The alloys with different amount of Zr added were investigated by DSC, microstructure observation, XRD, micro-hardness testing, calculation of the lattice parameters and bending test, then their elastic performance was measured and evaluated.The results indicated that the alloys exploited were composed of aβ-phase matrix and some needle-shapedα-phase precipitation with same ball-shapedα-phase segregation at grain interface. The addiction of Zr element influenced theα/βtransformation temperature. The Zr element could fine the grains of the alloys after homogenizing, consequently enhancing the mechanics properties. At the homogenizing state and the hot-rolling state, the hardness of the alloys decreased firstly and increased lastly along with the addition of Zr, with a minimum at 3at% Zr. Among the three treatment states, homogenizing state, hot-rolling state and normalizing state, the homogenizing state had a highest hardness. And the hot-rolling had the lowest hardness, and the hardness rose after normalization. The lattice parameters increased along with the increase of Zr content. The homogenizing had largest lattice parameters, while the hot-rolling and normalization decreased the parameters through decreasing defect in the alloys then relaxing the structure. The elastic resilience reached its best at 3 at% Zr. Generally, the elastic resilience became better with the annealing temperature rising except an abnormity at 3 at% Zr. It was related to the Ms temperature of alloys which was slightly lower than the room temperature.