烧结工艺对医用Ti-Nb-Ta-Zr合金微观结构及性能的影响

Effect of sintering process on microstructure and properties of medical Ti-Nb-Ta-Zr alloy

低模量β钛合金因具有优良的生物相容性成为目前生物医用植入材料的研究热点。其中,Ti-Nb-TaZr因含无毒元素,且具有强度高、塑性好等优点,在生物材料领域得到广泛的发展。本文采用传统粉末冶金法制备Ti-35Nb-7Zr-5Ta合金,结合显微硬度分布,根据均匀性指数和硬度变化系数分析相分布均匀程度,开展烧结工艺对钛合金微观结构与力学性能的影响研究。结果表明:随烧结温度的提高和烧结时间的延长,基体小孔隙尺寸逐渐减小并消失,相组成及分布发生了相应的变化,Ti-35Nb-7Zr-5Ta合金压缩弹性模量为(4.77±0.48)^(7.4±0.81)GPa,先增大后减小,接近松质骨弹性模量。在模拟体液环境下,烧结态Ti-35Nb-7Zr-5Ta合金阻抗谱呈现半容抗弧特征,相位角在较宽的频域10-1~102Hz之间存在峰值,表现出较高的耐蚀性能,为医用钛合金的生物力学性能研究提供理论基础。

β titanium alloy with low modulus has become a research hotspot in biomedical implant materials because of its excellent biocompatibility. Ti-Nb-Ta-Zr alloy with non-toxic alloying elements has been developed widely for biomaterials due to its high strength and significant plasticity. In this paper,Ti-35 Nb-7 Zr-5 Ta alloy was prepared by traditional powder metallurgy method in order to further regulate the uniformity. Based on the distribution of microhardness,the uniformity of phase distribution was analyzed according to the uniformity index and hardness variation coefficient. The effect of sintering process on the microstructure and mechanical properties of Ti-35 Nb-7 Zr-5 Ta alloy was studied. The experimental results show that with the increase of sintering temperature and holding time,the pore size of the matrix decreases gradually or even disappears,resulting in the phase compositions and distribution changing accordingly. The Young’s modulus of Ti-35 Nb-7 Zr-5 Ta alloy increases firstly and then decreases within(4.77±0.48)-(7.4±0.81)GPa,which is close to that of cancellous bone. In the simulated body fluid environment,the impedance spectrum of the sintered Ti-35 Nb-7 Zr-5 Ta alloy exhibits a semi-capacitive arc-resistance characteristic,and the phase angle has a peak value in the wide frequency domain of 10-1-102 Hz. It indicates that the sintered Ti-35 Nb-7 Zr-5 Ta alloy has high corrosion resistance and provides a theoretical basis for the study of biomechanical properties of medical titanium alloys.