Effect of Nb addition on microstructure, mechanical properties and castability of β-type Ti-Mo alloys

To develop novel β-type biomedical titanium alloys, a series of Ti-15Mo-xNb alloys(x=0, 5, 10 and 15, mass fraction in %) were designed and prepared by using vacuum arc melting method. The present study focused on the effect of Nb addition on the microstructure, mechanical properties and castability of Ti-15Mo alloy. Phase analysis and microstructure observation show that all the alloys consist of single β phase and the equiaxed β grain is refined with increasing Nb content. These β-type Ti-15Mo-xNb alloys exhibit good plasticity and rather low compression elastic modulus (in the range of 18.388-19.365 GPa). After Nb addition, the compression yield strength of the alloys increases. With increasing Nb content, the micro-hardness of the alloys decreases. The alloys exhibit obvious fibrous strip microstructure after cold compression deformation. The castability test shows that the castability of the alloys after Nb addition decreases and that of the Ti-15Mo alloy is the highest (92.01%).