B/Y复合微合金化高温钛合金显微组织及性能研究

Research on Microstructure and Properties of B/Y Composite Microalloyed High Temperature Titanium Alloy

研究了B/Y复合微量添加对高温钛合金凝固过程及显微组织的影响,分析了不同变形温度下高温钛合金的显微组织演变过程,测试了高温钛合金在室温和650℃下的拉伸性能。结果表明,B/Y微量复合添加使高温钛合金凝固过程中产生成分过冷,形成了包裹于β晶界的链状TiB增强相和晶界、晶内弥散分布的稀土氧化物颗粒,显著细化了原始β晶粒,抑制了β晶界的移动,使晶内析出的α片层长径比减小。不同温度轴向压缩变形后,高温钛合金饼坯不同位置处显微组织存在不均匀现象,TiB增强相促进了次生α相的球化。力学性能结果分析表明,两相区变形合金具有较好的强塑性匹配,B/Y复合添加后高温钛合金650℃拉伸强度得到明显提升。

The effect of B/Y composite trace addition on the solidification process and microstructure of high temperature titanium alloy was studied.The microstructure evolution process of high temperature titanium alloy at different deformation temperatures is analyzed.The tensile properties at room temperature and 650℃were tested.The results show that the micro-composite addition of B/Y leads to component undercooling during the solidification of high temperature titanium alloys,forming chain-like TiB reinforcing phases wrapped inβgrain boundaries and rare earth oxide particles dispersed in the grain boundaries and within the grains.The originalβgrains are refined,the movement ofβgrains boundaries is inhibited,and the aspect ratio of theαlamella precipitated in the crystal is reduced.After single step axial deformation at different temperatures,there are inhomogeneous microstructures at different positions of the hightemperature titanium alloy cake blank.The TiB reinforcement phase promotes the spheroidization of the secondaryαphase.The results of mechanical properties and the analysis of the tensile properties show that the deformed alloy in the twophase zone has a good strong plastic matching,and the tensile strength of the high temperature titanium alloy at 650℃is significantly improved after the B/Y composite addition.