Ti2AlNb与GH4169合金的可靠连接对降低飞行器重量、提高飞行效率,并拓展Ti2AlNb合金的应用范围有重要意义.针对钛铝系合金与镍基高温合金焊后接头易产生较大残余应力和多种TiNi脆性金属间化合物的问题,本研究基于界面相容性原则设计了类Ti元素与类Ni元素接近1∶1的(TiZrHf)50(NiCu)45Al5高熵非晶钎料,研究不同钎料成分和钎焊温度对Ti2AlNb与GH4169合金钎焊接头界面组织及性能的影响规律.结果表明:(TiZrHf)50(NiCu)45Al5钎料钎焊接头典型界面组织为Ti2AlNb合金/B2+固溶了 Ni 和 Cu 元素的 Ti2AlNb 相(Ⅰ 区)/(Ti,Zr,Hf)(Ni,Cu,Al)2+(Ti,Zr,Hf)(Ni,Cu)2(Ⅱ 区)/(Ni,Cr,Fe,Ti)ss+(Ni,Cr,Fe)ss(Ⅲ区)/GH4169合金.钎料成分和钎焊温度分别对钎缝Ⅱ区反应物相形成与反应物相组织演变有较大影响.采用(TiZrHf)30(NiCu)65Al5 钎料钎缝 Ⅱ 区主要由(Ti,Zr)(Ni,Cu,Al)2 相、Al(Ni,Cu)2Ti 相和 Ti(Ni,Cu)2 相组成,采用(TiZrHf)40(NiCu)55Al5钎料钎缝Ⅱ区主要为(Ti,Zr,Hf)(Ni,Cu)相.随钎焊温度升高,钎缝Ⅱ区厚度呈现先减小后增加的趋势.采用(TiZrHf)50(NiCu)45Al5钎料钎焊接头在1 035 ℃/15 min时剪切强度达到最大为305 MPa.断裂主要发生在母材与钎料的界面处,随钎焊温度升高,接头断裂位置逐渐转移至钎缝Ⅱ区,断口形貌为典型的解理断裂特征.钎焊接头界面组织的形成机理可划分为原子的固态扩散、液相生成与冶金反应、等温扩散凝固和反应物相生长与演变四个阶段.
Effects of Brazing Filler Composition and Brazing Temperature on the Microstructure and Mechanical Properties of Ti2AINb and GH4169 Alloy Brazed Joints
Sound joining of Ti2AlNb alloy to GH4169 alloy is crucial for reducing the weight of aircraft,enhancing flight efficiency,and expanding the application range of Ti2AlNb alloy.Addressing the issue of significant residual stresses and the formation of various brittle TiNi intermetallic compounds in joints between titanium-aluminum alloys and nickel-based superalloys after welding,this study designed a high-entropy amorphous brazing filler with an approximate 1∶1 ratio of Ti-group elements to Ni-group elements,specifically(TiZrHf)5o(NiCu)45Al5,based on the principle of interfacial compatibility.The research focused on the effects of different brazing filler compositions and brazing temperatures on the interfacial microstructure and properties of brazed joints between Ti2AlNb and GH4169 alloys.The results indicated that the typical interfacial structure of brazed joints using(TiZrHf)5o(NiCu)45Al5 consisted of Ti2AlNb alloy/B2 phase dissolved with Ni and Cu(Zone Ⅰ)/(Ti,Zr,Hf)(Ni,Cu,Al)2+(Ti,Zr,Hf)(Ni,Cu)2(Zone Ⅱ)/(Ni,Cr,Fe,Ti)ss+(Ni,Cr,Fe)ss(Zone Ⅲ)/GH4169 alloy.The composition of the brazing filler and the brazing temperature significantly influenced the formation and evolution of reactive phases in Zone Ⅱ of the brazed seam.Using(TiZrHf)30(NiCu)65Al5,Zone Ⅱ primarily consisted of(Ti,Zr)(Ni,Cu,Al)2,Al(Ni,Cu)2Ti,and Ti(Ni,Cu)2 phases,while using(TiZrHf)40(NiCu)55Al5,Zone Ⅱ predominantly featured(Ti,Zr,Hf)(Ni,Cu)phases.As the brazing temperature increased,the thickness of Zone Ⅱ first decreased and then increased.Brazed joints using(TiZrHf)5o(NiCu)45Al5 reached a maximum shear strength of 305 MPa at 1 035 ℃ for 15 min.Fracture primarily occurred at the interface between the base material and the brazing filler,and with increasing brazing temperature,the fracture location gradually shifted to Zone Ⅱ,displaying typical cleavage fracture characteristics.The formation mechanism of the joint interface structure could be categorized into four stages:solid-state diffusion of atoms,formation of liquid phase and metallurgical reactions,isothermal diffusion solidification,and growth and evolution of reactive phases.
dissimilar material joiningdesign of filler metalbrazinginterface microstructuremechanical properties
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