Second-phase-dependent grain refinement in Ti–25Nb–3Mo–3Zr–2Sn alloy and its enhanced osteoblast response

摘要

Ti–25Nb–3Mo–3Zr–2Sn (TLM) substrates, which consist of pure β phase and duplex α + β phases were achieved by different heat treatment. Different substrates with and without α phase were subjected to surface mechanical attrition treatment (SMAT) for 5 and 30 min, respectively. Investigated by transmission electron microscopy (TEM), it is found that the content andmorphology ofαphase in the TLMsubstrates play crucial roles in nanocrystallization of the alloy. During SMAT, the substrates composed of duplex α + β phases aremuch easier to nanocrystallized than that composed of pure β phase, and the duplex-phase substrate containing 35 vt.% α needles is more inclined to grain refinement than those substrates containing 27 vt.% α cobbles and 31 vt.% α needles.Accompaniedwith the nanocrystallization in the surface layers of the duplex-phase substrates, the stress induced α-to-β phase transition occurs. In addition, employing hFOB1.19 cells, the behaviors of osteoblasts on the unSMATed and as-SMATed surfaces were evaluated by examining the morphology and viability of the cells. It shows that the SMAT-induced grain refinement in the surface layer of the alloy can significantly improve the osteoblast response. Our study lays the foundation for nanostructuring β titanium alloys to be used as biomedical implants.