文摘
Ti-25Nb-3Mo-3Zr-2Sn (TLM) substrates, which consist of pure 尾 phase and duplex 伪 + 尾 phases were achieved by different heat treatment. Different substrates with and without 伪 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 and morphology of 伪 phase in the TLM substrates play crucial roles in nanocrystallization of the alloy. During SMAT, the substrates composed of duplex 伪 + 尾 phases are much easier to nanocrystallized than that composed of pure 尾 phase, and the duplex-phase substrate containing 35 vt.% 伪 needles is more inclined to grain refinement than those substrates containing 27 vt.% 伪 cobbles and 31 vt.% 伪 needles. Accompanied with the nanocrystallization in the surface layers of the duplex-phase substrates, the stress induced 伪-to-尾 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 尾 titanium alloys to be used as biomedical implants.