合金元素对机械合金化和放电等离子烧结Ti-Nb基合金显微组织的影响

Effects of alloying elements on microstructure of Ti-Nb alloy during the mechanical alloying and spark plasma sintering processing

β-Ti型结构的钛基材料在生物材料领域具有广泛的应用前景。本文采用机械合金化法和放电等离子烧结制备β-Ti型Ti-Nb基合金,研究不同Nb,Fe含量对合金显微组织及力学性能的影响。利用扫描电镜(SEM)、X射线衍射仪(XRD)和透射电镜(TEM)等手段分析合金的显微组织变化情况。结果表明:机械合金化过程中,粉末的平均粒度减小,当球磨时间超过60 h时粉末易发生团聚。当球磨转速为300 r/min,球料比为12:1,Ti和Nb的质量分数分别为64%和24%时,球磨100 h后制备的粉体材料中具有一定体积的非晶相。该粉末在1 000℃下通过放电等离子烧结(SPS)制备具有均匀细小的球状晶粒组织的Ti-Nb合金,其强度、伸长率和弹性模量分别为2 180MPa,6.7%和55 GPa。通过控制Nb,Fe的含量,可以促进β-Ti相形成,获得高强度和低杨氏模量的Ti-Nb合金。

β-Ti type titanium alloys have a great potential for biomedical application.β-Ti type Ti-Nb alloy was prepared by mechanical alloying and spark plasma sintering. The effects of Nb and Fe contents on microstructure and mechanical properties of Ti-Nb alloy were studied by using scanning electron microscopy （SEM）, X-ray diffractometer （XRD） and transmission electron microscopy （TEM）. The results show that in the process of ball-milling, the average particle size of powders decreases, and the powders even agglormerate when the milling time is over 60 h. When the ball-milling speed is 300r/min, the ratio of ball and material is 12：1, the mass fractions of Ti and Nb are 64% and 24%, respectively. When the ball-milling time is 100 h, the milled powder consists of partly amorphous phase. Through the spark plasma sintering （SPS） processing at 1000℃, the Ti-Nb alloy is prepared with a uniform fine microstructure. Meanwhile, it exhibits yield strength of 2180 MPa, elongation of 6.7% and low Young’s modulus of 55 GPa. Controlling Nb and Fe content can promote the formation ofβ-Ti phase, which can help obtain high strength and low Young’s modulus alloy.