镁含量对粉末冶金Ti-Mg合金组织及性能的影响

摘要 背景：采用粉末冶金工艺可制备出高强度的钛合金，但制备的合金仍然存在着含有毒元素或弹性模量偏高等问题。 目的：制备具有无毒、弹性模量接近于人体骨骼、强度符合人体植入物要求的Ti-Mg合金，并探讨镁含量对合金组织和力学性能的影响。 方法：采用粉末冶金工艺将不同质量分数Mg粉与Ti粉进行配比，制备综合性能良好的新型医用Ti-Mg合金。通过光学显微镜、扫描电镜和X射线衍射仪等对烧结体的孔隙率、断口形貌和相组成进行观察，并测试合金的抗弯强度，冲击韧性和硬度等力学性能。 结果与结论：随着镁质量分数的增加，容许应变先降低后增加，当镁质量分数为10%时，试样的容许应变为0.97%，最接近于皮质骨的容许应变0.67%；合金的孔隙率从18.3%降到了3.8%，孔洞更加圆滑，孔洞分部更加均匀。且随着镁质量分数的增加，合金的硬度、弯曲强度和模量具有相似的变化规律：即当镁质量分数低于10%时，变化不大，随着镁质量分数的继续增加明显降低，而后趋于稳定。当镁元素质量分数为10%时，合金的硬度、抗弯强度、冲击韧性均满足人体植入的力学性能要求，并且其弯曲模量和容许应变最接近于人体骨骼，显示了较好的生物力学相容性。 关键词：钛镁合金；粉末冶金；孔隙率；力学性能；生物材料

Effect of magnesium content on microstructure and properties of powder metallurgy Ti-Mg alloy

Abstract BACKGROUND: High-strength titanium alloy can be prepared by using powder metallurgy technique, but there are still some problems such as containing toxic elements or high elastic modulus in prepared alloys. OBJECTIVE: A new Ti-Mg alloy with non-toxic and elastic modulus which is close to human bones and strengths satisfy the requirements for human body implants was successfully prepared by means of powder metallurgy technology, and the effects of magnesium content on the microstructure and mechanical properties of Ti-Mg alloy were systematically studied. METHODS: The Mg powder and Ti powder in different mass ratios were prepared by powder metallurgy process to get a new integrated medical Ti-Mg alloy with excellent comprehensive properties. The porosity, fracture surface morphology and phase constituents of samples were observed by optical microscopy, scanning electron microscopy and X-ray diffraction, and the mechanical properties including bending strength, impact toughness and hardness of the alloys were measured. RESULTS AND CONCLUSION: Magnesium mass increasing firstly decreased and then increased admissible strain. When magnesium mass was 10%, admissible strain was 0.97%, which was highly closed to 0.67% of cortical bone. The porosity decreased from 18.3% to 3.8%, the holes became more tact and distributes more uniform, with the increased of mass ratio of magnesium. And with the increased of mass ratio of magnesium, the hardness, bending strength and elastic modulus of alloys with similar pattern of change, there were little changed when the mass fraction of magnesium less than 10%, they decreased significantly and then tended to stable with the continued to increased of magnesium mass fraction. While the admissible strain firstly decreased and then increased, with the increased of the mass fraction of magnesium. When the mass fraction of magnesium was 10%, the hardness, bending strength, impact toughness satisfied the mechanical requirements for human body implants, and the bending strength and admissible strain were close to human bones, which indicated well biomechanical compatibility.