整形外科用摩擦焊纯钛/镁合金螺钉的力学性能、腐蚀行为和生物相容性

Mechanical properties,corrosion behavior and biocompatibility of orthopedic pure titanium−magnesium alloy screw prepared by friction welding

在转速为1100、1200和1300 r/min条件下,通过旋转摩擦焊将生物可降解镁合金与商业纯钛异种焊接后加工成螺钉,研究异种接头的性能。金相分析结果表明钛/镁合金接头处连接较好。在镁合金一侧观察到焊缝中心区(WCZ)、动态再结晶区(DRX)、热力影响区(TMAZ)和局部变形区(PDZ)。在1300 r/min转速下制备的螺钉具有最高的拉伸强度和剪切强度,分别为173和103.2 MPa。钛/镁合金异种摩擦焊接头在含有Ti3Al的金属间化合物区附近失效。由于晶粒细化(8.57μm)和钛颗粒的影响,从镁合金一侧到焊缝区,硬度值逐渐增大;而钛一侧的硬度值保持不变。浸泡实验显示钛/镁合金接头的腐蚀速率高于纯钛与镁合金的腐蚀速率。此外,1300 r/min转速下制备的接头由于其更好的耐腐蚀性能,显示出更好的生物相容性和细胞活性(98.12%)。

The dissimilar joining of biodegradable magnesium alloy to pure commercial titanium by rotational friction welding with rotational speeds of 1100,1200 and 1300 r/min for the production of bio-screw was investigated.The metallographic analysis revealed that a good joining was obtained at the Ti/Mg alloy joint.On the magnesium alloy side,various regions such as the weld center zone(WCZ),dynamic recrystallization zone(DRX),thermo-mechanically affected zone(TMAZ)and partially deformed zone(PDZ)were observed.The highest tensile and shear strengths were 173 and 103.2 MPa,respectively at a rotational speed of 1300 r/min.The Ti/Mg alloy dissimilar friction welded joint failed at the vicinity of the intermetallic zone containing Ti3Al phase.The hardness values from the base metal magnesium alloy to the joining point increased mainly due to grain refinement(8.57μm in diameter)and the presence of titanium particles,while the hardness values were constant on the titanium side.It was also found that the corrosion rate of the Ti/Mg alloy joint was higher compared with that of the Ti and Mg alloy from the immersion studies.Additionally,the sample with a rotational speed of 1300 r/min showed better biocompatibility and a cell viability of 98.12%due to better corrosion resistance.