Achieving ultralow elastic modulus in TiNi alloy by controlling nanoscale martensite phase

Fatigue Crack Growth and Fracture of Internal Fixation Materials in In Vivo Environments—A Review

“…Compared with normal bone tissue, the moduli mismatch is more serious in osteoporosis with anticipated high rates of implant crack growth and failure. Thus, some novel implants with ultra-low elastic modulus like Ti-24Nb-4Zr-7.9Sn (42 GPa) [ 64 ], Ti-24Nb-4Zr-8Sn (49 GPa) [ 65 ], and Ti-50.7at%Ni (29 GPa) [ 66 ] were invented for orthopedic applications by biomaterial scientists, which were able to relieve the “stress shielding effect” caused by the modulus mismatch and suppress bone resorption for long term implantation. Mazigi et al concluded that the Ti-35Nb-3Zr alloy (85 GPa) with a direct biocompatibility test exhibited a greater potential for long-term successful performance compared to the TAV [ 67 ].…”

Effects of strain and electropulse duration on elastic modulus of TiNi alloy

“…And the incipient E decreases continuously from 42 to 30 GPa with the rolling strain further increasing from 0.92 to 1.70 (Figure 5(b) curves C and D). Researches have been reported that the monoclinic martensitic B19 ′ phase presents a very low elastic modulus (∼20–50 GPa), which is only half that of cubic austenitic B2 phase [18,31,32]. With the increase of rolling strain, the volume fraction of B19 ′ phase gradually increased (see Figure 2 spectra (b–d) and Figure 3), thus resulted in the decrease in elastic modulus of EPR TiNi alloy.…”

“…As a result, an ultralow elastic modulus of E ∼ 29 GPa was successfully realised in the alloy. The low elastic modulus can be attributed to its non-equilibrium martensite phases with low elastic modulus as some work reported [18][19][20]. Although the low elastic modulus was realised in TiNi alloy [18], little is known on the effect of deformation parameters on the microstructure and mechanical properties.…”

“…The low elastic modulus can be attributed to its non-equilibrium martensite phases with low elastic modulus as some work reported [18][19][20]. Although the low elastic modulus was realised in TiNi alloy [18], little is known on the effect of deformation parameters on the microstructure and mechanical properties. These information are very important for the microstructure control and medical applications.…”

“…However, there are few reports with regard to the elastic modulus of metallic biomaterials by using SPD technique. Recently, the electroplastic rolling (EPR) was employed to tailor the elastic properties of Ti alloys by our group [18]. Different from conventional phase tailoring strategies, the TiNi alloy was deformed by EPR at room temperature.…”