Microstructural evolution and mechanical properties of Ti-Zr beta titanium alloy after laser surface remelting

摘要

The effects of laser surface remelting (LSR) on the microstructural evolution and surface mechanical properties of Ti-Zr beta titanium alloy were investigated. The surfaces of the Ti-Zr alloy was re-melted using a CO_2 laser. X-ray diffraction, Scanning electron microscope, Transmission electron microscope, nanoindentation, and microhardness analyses were performed to evaluate the microstructural and mechanical properties of the alloy. The results showed that the alloy microstructure in the remelting region was greatly refined and homogeneous compared with that in the base material because of the rapid remelting and resolidifying. Meanwhile, the metastable hexagonal co phases with the size of 20-50 nm was found and uniformly distributed throughout the 0 matrix after LSR. Phase transformation and microstructural refinement were the major microstructural changes in the alloys after LSR. The microhardness and elastic modulus in the remelted region clearly increased by 92.9% and 21.78%, respectively, compared with those in the region without laser processing. The strengthening effect of LSR on the mechanical properties of the Ti-Zr alloy was also addressed. Our results indicated that LSR was an effective method of improving the surface mechanical properties of alloys.