Ti811表面TC4激光熔覆层中β相偏析行为研究
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摘要
在Ti811合金表面,利用同步送粉激光熔覆技术,制备了TC4激光熔覆层。利用X射线衍射仪、扫描电镜和能谱分析仪等手段分析了涂层组织和β相偏析行为。结果表明,涂层组织出现了典型的β相偏析现象,在涂层中以大块的暗色区域存在;涂层的非β相偏析区微观组织呈现出魏氏体结构,在α-Ti组成的晶界中分布着大量针状马氏体α′-Ti相和少量残留β-Ti相,纳米α_2相弥散分布在涂层中;涂层的β相偏析区域出现了大面积残留β-Ti相,晶界α-Ti相和针状马氏体α′-Ti相的特征和数量明显减少,主要是因为激光熔覆形成的熔池冷却速度极快,原始β晶粒来不及相变所导致。
The TC4 laser cladding layer was prepared on the surface of Ti811 alloys with coaxial powder feeding.The microstructure andβ-phase segregation of the coating were analyzed by using X-ray diffraction(XRD),scanning electron microscope(SEM)and energy dispersive spectrometer(EDS).The results reveal that,the typicalβ-phase segregation occurs in the cladding layer and appears as the large dark area.The microstructure of the non-β-phase segregation region of the cladding layer shows a typical widmanstatten structure.Many accicular martensiticα′-Ti and trace residualβ-Ti are distributed in the grain boundaries ofα-Ti,and nano particles ofα2 phase are dispersed in the cladding layer.In theβ-phase segregation region of the coating,a large area of residualβ-Ti appears in the microstructure while the grain boundaries ofα-Ti and accicular martensiticα′-Ti are obviously reduced,which are attributed to the molten pool formed by laser cladding cooling in a vary fast way and leaving no time for the phase transition of originalβgrains.
The TC4 laser cladding layer was prepared on the surface of Ti811 alloys with coaxial powder feeding.The microstructure andβ-phase segregation of the coating were analyzed by using X-ray diffraction(XRD),scanning electron microscope(SEM)and energy dispersive spectrometer(EDS).The results reveal that,the typicalβ-phase segregation occurs in the cladding layer and appears as the large dark area.The microstructure of the non-β-phase segregation region of the cladding layer shows a typical widmanstatten structure.Many accicular martensiticα′-Ti and trace residualβ-Ti are distributed in the grain boundaries ofα-Ti,and nano particles ofα2 phase are dispersed in the cladding layer.In theβ-phase segregation region of the coating,a large area of residualβ-Ti appears in the microstructure while the grain boundaries ofα-Ti and accicular martensiticα′-Ti are obviously reduced,which are attributed to the molten pool formed by laser cladding cooling in a vary fast way and leaving no time for the phase transition of originalβgrains.
引文
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[2]金和喜,魏克湘,李建明,等.航空用钛合金研究进展[J].中国有色金属学报,2015,25(2):280-292.
[3]KURODA T,HORINOUCHI T,IWAGI O,et al.Microstructure in weld heat-affected zone of beta titanium alloy[J].Transactions of JWRI.,1990,19:79-86.
[4]巩水利.先进激光加工技术[M].北京:航空工业出版社,2016.
[5]孙荣禄,杨贤金.TC4钛合金激光熔覆TiC+M涂层组织和耐磨性能研究[J].材料热处理学报,2006(1):96-99,137.
[6]LI J N,GONG S L,SHAN F H,et al.Analysis of microstructure performance of laser clad Ti3Al matrix composite coating on aviation titanium alloy[J].Aeronautical Manufacturing Technology,2013,16:76-80.
[7]张喜燕,赵永庆,白晨光.钛合金及应用[M].北京:化学工业出版社,2005.
[8]赵永庆,陈永楠,张学敏.钛合金相变及热处理[M].长沙:中南大学出版社,2012.
[9]孙峰.Ti60钛合金相变动力学及组织演变研究[D].西安:西北工业大学,2015.
[10]俞汉清,曾卫东,胡鲜红,等.钛合金中的β斑点及其研究方法[J].稀有金属材料与工程,1995(5):23-27.
[11]朱知寿.新型航空高性能钛合金材料技术研究与发展[M].北京:航空工业出版社,2013.
[12]王孟光,周洪强,姜建伟.Ti-1023合金铸锭的铁偏析[J].中国有色金属学报,2010,20(S1):784-788.
[13]杨昭.熔炼工艺对Ti-1023合金中Fe的均匀性影响[J].上海钢研,2006(4):10-12.
[14]张伟强.固态金属及合金中的相变[M].北京:国防工业出版社,2016.
[15]张虎.热处理工艺对新型高强β钛合金组织和性能的影响[D].西安:西安建筑科技大学,2013.