Ta含量对Ti-6Al-3Nb-2Zr-1Mo合金力学性能和腐蚀性能的影响

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

摘要:

系统研究了Ti-6Al-3Nb-2Zr-1Mo-xTa (x=0、0.5、1.0、3.0和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-xTa (x = 0、0.5、1.0和3.0)均获得双态组织。XRD和TEM选择区域电子衍射表明，在添加Ta元素后，Ti-6Al-3Nb-2Zr-1Mo-xTa合金没有新相产生。对于双态组织Ti-6Al-3Nb-Zr-1M0-xTa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1.0wt %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-xTa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。

Abstract:

The microstructure, tensile properties, Charpy impact toughness and corrosion resistance of Ti-6Al-3Nb-2Zr-1Mo-xTa (x=0, 0.5, 1.0, 3.0 and 5.0) alloys were investigated. The results indicated that, except for the lamellar structure Ti-6Al-3Nb-2Zr-1Mo-5Ta alloy, the bimodal structure was obtained in Ti-6Al-3Nb-2Zr-1Mo-xTa (x=0, 0.5, 1.0 and 3.0) after hot deformation during α+β region. The results of XRD pattern and selected area electron diffraction indicate that, no new phase was indentified after adding Ta element although the XRD peaks of both α and β phases shift toward the low angle side as the increasing of Ta content. For the bimodal structure Ti-6Al-3Nb-Zr-1M0-xTa alloy, the yield strength (YS), ultimate tensile strength (UTS) and microhardness increase due to the increasing of molybdenum equivalent (Mo[eq]). The impact absorb energy dependence on the Ta content is opposite to YS, UTS and microhardness, and their value are consistent with the area of shear lip region on the impact fracture surface. when the Ta content is more than 1.0 wt%, the resistance to corrosion of Ti-6Al-3Nb-2Zr-1Mo-xTa alloys decrease due to the increasing of standard balancing potential difference between α and β phase as the Ta content increasing. After potentiodynamic polarization tests, the samples surface area are covered with lots of corrosion pits, which are mainly distributed in the αp grain interior and α/β interface. Combining YS, impact toughness and corrosion performance, Ti-6Al-3Nb-2Zr-1Mo-1Ta alloy exhibits the best compatibility, suggests its promising potential for marine applications.