Microstructure and pseudoelasticity of Ti-Nb-Si based alloys with biocompatible alloying elements

We have newly designed a metastable beta Ti-Nb-Si based alloy with biocompatible alloying elements without containing toxic V or Al for orthodontic applications. Microstructures and pseudoelastic behavior of beta Ti-Nb-Si alloys were investigated in order to correlate the pseudoelasticity and microstructure together with martensite transformation. Nb and Si alloying to the present alloy make beta phase to be stable. It is found that metastable beta phase is favorable to display pseudoelastic behavior than stable or unstable beta phase. Optical microscope (OM) revealed that stress-induced martensitic transformation takes place during room temperature deformation in the present alloys. Within the alloys having beta (bcc) phase studied the alloy with low content of Si appeared to exhibit a dominant behavior for stress-induced martensitic transformation than that with high content of Si. After recrystallization heat treatment pseudoelasticity of the present alloy appeared to be prominent. The pseudoelastic behavior of this alloy was correlated to the stress-induced martensite transformation. Pseudoelasticity of the present alloys is hindered by the development of {001} < 110 > rotated cube component.