Ta含量对Ti-6Al-3Nb-2Zr-1Mo-xTa合金力学性能和腐蚀性能的影响

系统研究了Ti-6Al-3Nb-2Zr-1Mo-x Ta(x=0,0.2,0.5,1.0,3.0,5.0)合金的微观组织、拉伸性能、夏比冲击韧性和耐海水腐蚀性。结果表明,经α+β两相区锻造后,Ti-6Al-3Nb-2Zr-1Mo-5Ta合金获得片层组织,Ti-6Al-3Nb-2Zr-1Mo-x Ta(x=0,0.2,0.5,1.0,3.0)均获得双态组织。XRD、TEM和选区电子衍射表明,在添加Ta元素后,Ti-6Al-3Nb-2Zr-1Mo-x Ta合金没有新相产生。对于双态组织Ti-6Al-3Nb-Zr-1M0-x Ta合金,随着Ta含量的增加,其Mo当量逐渐增加,导致其屈服强度、抗拉强度和显微硬度均有所提高。而Ta含量对冲击吸收功的影响规律与屈服强度和抗拉强度的影响规律相反,其大小与冲击断口剪切唇区面积一致。当Ta含量超过1.0%(质量分数)时,由于α和β相之间的标准平衡电位差逐渐增大,Ti-6Al-3Nb-2Zr-1Mo-x Ta合金的耐海水腐蚀逐渐降低。综合考虑强度、冲击韧性和耐海水腐蚀性能,Ti-6Al-3Nb-2Zr-1Mo-1Ta合金综合匹配性最好,具有良好的海洋工程应用潜力。

Effect of tantalum content on the mechanical and corrosion behavior of Ti-6Al-3Nb-2Zr-1Mo-xTa alloys

The microstructure,tensile properties,Charpy impact toughness and corrosion resistance of Ti-6 Al-3 Nb-2 Zr-1 Mo-x Ta(x=0,0.2,0.5,1.0,3.0,5.0)alloys were investigated.The results indicate that except Ti-6 Al-3 Nb-2 Zr-1 Mo-5 Ta alloy with lamellar structure,the bimodal structure is observed in Ti-6 Al-3 Nb-2 Zr-1 Mo-x Ta(x=0,0.2,0.5,1.0,3.0)after hot deformation atα+βregion.The results of XRD patterns and selected area electron diffraction indicate that no new phase is identified after adding Ta,although the peaks of bothαandβphases shift toward the low angle side with the increase of Ta content.For the Ti-6 Al-3 Nb-Zr-1 Mo-x Ta alloy with bimodal structure,the yield strength(YS),ultimate tensile strength(UTS)and microhardness increase due to the increase of molybdenum equivalent(Mo_[eq]).The influence trend of the Ta content on impact absorb energy is opposite to that on YS,UTS and microhardness.YS,UTS and microhardness are in consistent with the area of shear lip region in the impact fracture surface.When the Ta content is more than 1.0 wt%,the corrosion resistance of Ti-6 Al-3 Nb-2 Zr-1 Mo-x Ta alloys decreases due to the increase of standard balancing potential difference betweenαandβphases.After potentiodynamic polarization tests,the sample surface area is covered with lots of corrosion pits,which are mainly distributed in theαp grain interior andα/βinterface.Combining YS,impact toughness and corrosion performance,Ti-6 Al-3 Nb-2 Zr-1 Mo-1 Ta alloy exhibits the optimized compatibility,suggesting its promising potential for marine applications.