微量Zr在铸造TiAl合金层片组织的分布特征  

Distribution of Minor Zr in Cast TiAl Alloy Lamellar Microstructure

作　　者：骆晨[1] 夏冰[1] 朱春雷[1] 李胜[1] 张继[1] 

机构地区：[1]钢铁研究总院高温材料研究所,北京100081

出　　处：《航天制造技术》2015年第3期4-7,共4页Aerospace Manufacturing Technology

基　　金：国家973资助项目(2011CB605503)

摘　　要：采用电子探针,研究了0.2at%Zr在铸造Ti-47.5A1-2.5V_1.0Cr（at%）合金层片组织的分布特征,并结合合金热等静压前后状态的组织观察,探索微量Zr提高铸造TiAl合金层片组织的持久性能的机理。结果表明：铸态层片组织Zr元素主要以两种浓度范围分布,其中0.047%~0.77%（mt%）浓度的Zr元素占总含量的92.3%,均匀分布于基体,而含量6.5%的0.77%~1.5%（mt%）浓度的Zr元素偏析在富Al的γ偏析区,形成枝晶偏析形貌。添加微量Zr,热等静压组织中等轴γ晶粒析出的体积分数由8%减少到3%,平均晶粒尺寸由44μm减少到25μm。微量Zr在层片组织富Al区域的偏析阻碍了热等静压过程中Al元素的扩散,抑制了等轴γ晶粒的析出和长大,是Zr提高铸造TiAl合金持久寿命的重要因素。The distribution of 0.2at%Zr in cast alloy Ti-47.5Al-2.5 V-1.0Cr（at.%） lamellar microstructure was investigated by electron probe microanalyzer,and combined with the hot isostatic pressing mirostructure analysis,the mechanism that minor Zr improved the creep rupture properties on TiAl alloy lamellar microstructure have been studied respectively.Results show that Zr elements mainly distributed two kinds of concentration in the lamellar microstructure,the concentration of 0.047%~0.77%（mt%） accounted for 92.3%of the total amount of Zr element,uniformly distributed in the matrix,while the concentration of 0.77%~1.5%（mt%） accounted for 6.5%practical segregated in the Al segregation area,formed the dendritic segregation morphology.In hot isostatic pressing treatment,adding Zr reduced the volume fraction of the precipitation of equiaxed gamma grain from 8%to 3%,reduced the average grain size from 44μm to 25μm.Minor Zr segregated in the Al segregation area,hindered the diffusion of Al element in hot isostatic pressing process,suppressesed equiaxed gamma grain precipitation and growing up,which is a important reason for Zr improving the creep rupture life of cast TiAl alloy lamellar microstructure.

关 键 词：TIAL合金 铸造层片组织 微量Zr 偏析 

分 类 号：TG292[金属学及工艺—铸造] V46[航空宇航科学与技术—航空宇航制造工程]