强流脉冲电子束作用下Ti2AlNb微观结构状态与耐腐蚀性能研究

Microstructure and Corrosion Properties of Ti2AlNb Irradiated by High Current Pulsed Electron Beam Treatment

利用强流脉冲电子束(HCPEB)对Ti2AlNb合金进行辐照处理,利用X射线衍射仪(XRD),场发射扫描电子显微镜(SEM),透射电子显微镜(TEM)对辐照后合金的显微组织结构进行分析,结果表明,辐照后表面形成大量火山状熔坑,随着辐照次数的增加,熔坑的密度显著减少,辐照后合金发生α+β→O相变,β和O相显著细化;辐照后表层形成了一层厚度约为4μm的重熔层,重熔层中Al发生过饱和固溶而富Al;辐照在亚表层产生高幅值的应力和温度梯度,造成亚表层发生强烈塑性变形,生成高密度的位错,孪晶和层错等缺陷结构。辐照后试样的耐腐蚀性能得到了提高,这主要归因于辐照后产生的表面净化效应和成分均匀化,表面富Al生成致密的Al_(2)O_(3)保护膜以及Al的增强扩散修复腐蚀过程中损耗的Al_(2)O_(3)膜,提高了Ti2AlNb合金的耐腐蚀性能。

Ti2AlNb alloy was treated with High Current Pulsed Electron Beam(HCPEB).The microstructure of the alloy after irradiation was analyzed by X-ray diffraction,Scanning electron microscopy and Transmission electron microscopy.The results showed that a large number of craters were formed on the surface after irradiation.The density of craters decreases significantly with the increase of irradiation times,and the alloy undergoα+β→O transformation after irradiation,theβand O phases are refined significantly.After irradiation,a remelting layer with a thickness of about 4μm was formed in the surface layer,and the aluminum in the remelting layer was supersaturated and formed an aluminum-rich layer.The irradiation produces high amplitude stress and temperature gradients in the subsurface layer,resulting in strong plastic deformation in the subsurface layer and the formation of high-density defect structures such as dislocation,twins and layer faults.The corrosion resistance of Ti2AlNb alloy is improved after irradiation,which is mainly attributed to the surface purification effect and composition homogenization after irradiation,the formation of dense Al_(2)O_(3)protective film from the surface of aluminum-rich,and the enhanced diffusion of aluminum to repair the Al_(2)O_(3)film lost in the corrosion process,which improves the corrosion resistance of Ti2AlNb alloy.