摘要
研究了TiAl及TiAl-9Nb合金在850℃下25%NaCl+75%Na2SO4(质量分数)熔盐中的热腐蚀行为,采用扫描电子显微镜(SEM)、能谱分析(EDS)和X射线衍射(XRD)分析了腐蚀产物膜的结构和相组成。结果表明:TiAl和TiAl-9Nb合金的腐蚀产物均主要由TiO2, Al2O3和少量的TiS组成,腐蚀产物膜结构疏松,容易剥落,对基体的保护性很差。在热腐蚀过程中, NaCl对TiAl和TiAl-9Nb合金的表面氧化膜造成了破坏,生成的Cl2导致了表面氧化膜的开裂;继而O和S对TiAl合金中的α2相、 TiAl-9Nb合金中的β相产生了内氧化、内硫化的选择性腐蚀。与普通TiAl合金相比, TiAl-9Nb合金具有更优异的抗热腐蚀性能,这归因于TiAl-9Nb合金中β相较高的Al含量以及β相与α2相之间组织结构的差异。
Hot corrosion behavior of TiAl and TiAl-9 Nb alloys in molten salt environment of 25%NaCl+75%Na2SO4(mass fraction)at 850℃was investigated.Scanning electron microscope(SEM),energy dispersive X-ray spectrometer(EDS)and X-ray diffractometer(XRD)were employed to investigate the surface morphologies,microstructures and phase constitutions of the corrosion films.The results show that the corrosion products of both TiAl and TiAl-9 Nb alloys were mainly composed of TiO2,Al2O3 and a small amount of TiS.The corrosion film was loose and easy to peel off,and thus had little protective effects to the substrate.During hot corrosion,NaCl broke the protective scales formed on TiAl and TiAl-9 Nb alloys by producing corrosive Cl2,and then,selective corrosion characterized by internal oxidation and internal sulfide occurred along theα2 phase in TiAl andβphase in TiAl-9 Nb.The higher concentration of Al inβphase in TiAl-9 Nb alloy than that ofα2 phase in TiAl alloy,as well as the structural differences between the two phases should be the main reasons responsible for the better hot corrosion resistance of TiAl-9 Nb than TiAl.
作者
李涌泉
耿桂宏
李宁
董福元
侯俊峰
Li Yongquan;Geng Guihong;Li Ning;Dong Fuyuan;Hou Junfeng(School of Material Science&Engineering,Beifang University of Nationalities,Yinchuan 750021,China)
出处
《稀有金属》
EI
CAS
CSCD
北大核心
2019年第6期571-576,共6页
Chinese Journal of Rare Metals
基金
宁夏高等学校科学技术研究项目(NGY2018-148)资助
