Effect of brazing temperature and brazing time on the microstructure and tensile strength of TiAl-based alloy joints with Ti-Zr-Cu-Ni amorphous alloy as filler metal

An amorphous Ti-37.5Zr-15Cu-15Ni (wt.%) ribbon fabricated by vacuum arc remelting and rapid solidification was used as filler metal to vacuum braze TiAl alloy (Ti-45Al-2Mn-2Nb-1B (at.%)). The effects of brazing temperature and time on the microstructure and strength of the joints were investigated in details. The typical brazed joint major consisted of three zones and the brazed joints mainly consisted of α_2-Ti₃Al phase, α-Ti phase and (Ti, Zr)₂(Cu, Ni) phase. When the brazing temperature varied from 910 °C to 1010 °C for 30 min, the tensile strength of the joint first increased and then decreased. With increasing the brazing time, the tensile strength of the joint increased. The maximum room temperature tensile strength was 468 MPa when the specimen was brazed at 930 °C for 60 min. All the fracture surfaces assumed typical brittle cleavage fracture characteristic. The fracture path varied with the brazing parameter and cracks preferred to initiate at (Ti, Zr)₂(Cu, Ni) phase and propagation path were mainly determined by the content and distribution of α-Ti phase and (Ti, Zr)₂(Cu, Ni) phase.     

Vacuum brazing of TZM alloy to ZrC particle reinforced W composite using Ti-28Ni eutectic brazing alloy

Reliable brazing of TZM alloy and ZrC particle reinforced (ZrC_p) W composite was achieved in this study by using Ti-28Ni eutectic brazing alloy. The typical interfacial microstructure of TZM/Ti-28Ni/ZrC_p-W brazed joint consisted of a Ti solid solution (Ti(s, s)) layer, a continuous Ti₂Ni layer and a diffusion layer mainly composed of W particles and (Ti, Zr)C particles. With an increase of brazing temperature, more ZrC particles and W particles entered the molten brazing alloy, which broadened the brazing seam and diminished the Ti₂Ni layer, resulting in the disappearance of the Ti₂Ni layer eventually. Meanwhile, more Ti(s, s) stripes were observed on the TZM side. The presence of continuous Ti₂Ni intermetallic phase and Ti(s, s) stripes structure in joints deteriorated the joining properties, which resulted in the formation of brittle fracture under shear test. In addition, the fracture path was related to the brazing temperature, and cracks initiate and propagate in the continuous Ti₂Ni layer at lower temperatures. However, the fracture path tended to be located at the TZM substrate close to the interface between TZM and the brazing seam when the brazing temperature exceeded 1040 °C. The optimal room temperature shear strength reached 120.5 MPa when brazed at 1040 °C for 10 min and the fracture surface exhibited cleavage fracture characteristics, and the shear strength at high temperature of 800 °C for the specimens with highest shear strength at room temperature reached 77.5 MPa.     

TC4/Ti60合金钎焊接头界面组织及力学性能

采用TiZrNiCu非晶钎料实现了TC4和Ti60异种钛合金的真空钎焊连接,利用扫描电子显微镜(SEM)、能谱仪(EDS)和X射线衍射仪(XRD)等分析手段研究了钎焊工艺参数对接头界面组织结构及力学性能的影响. 结果表明,TC4/TiZrNiCu/Ti60钎焊接头的典型界面结构为:TC4/α-Ti+β-Ti+(Ti,Zr)2(Ni,Cu)/Ti60. 随着钎焊温度升高或保温时间延长,片层状α+β相逐渐填充整条钎缝,(Ti,Zr)2(Ni,Cu)相含量减少且分布更加均匀. 接头室温抗拉强度随钎焊温度或保温时间的增加均先增大后减小,在990 ℃/10 min钎焊条件下所获接头抗拉强度达到最大为535.3 MPa. 断口分析结果表明,断裂位于钎缝中,断裂方式为脆性断裂.     

Vacuum brazing of TiAl-based intermetallics with Ti–Zr–Cu–Ni–Co amorphous alloy as filler metal

An amorphous Ti41.7–Zr26.7–Cu14.7–Ni13.8–Co3.1 (wt%) ribbon fabricated by melt spinning was used as filler to vacuum braze Ti–48Al–2Nb–2Cr (at%) intermetallics. The influences of brazing temperature and time on the microstructure and strength of the joints were investigated. It is found that intermetallic phases of Ti₃Al and γ-Ti₂Cu/Ti₂Ni form in the brazed joints. The tensile strength of the joint first increases and then decreases with the increase of the brazing temperature in the range of 900–1050 °C and the brazing time varying from 3 to 15 min. The maximum tensile strength at room temperature is 316 MPa when the joint is brazed at 950 °C for 5 min. Cleavage facets are widely observed on all of the fracture surfaces of the brazed joints. The fracture path varies with the brazing condition and cracks prefer to initiate at locations with relatively high content of γ-Ti₂Cu/Ti₂Ni phases and propagate through them.     

TC4／Ag-Cu—Ti／1Cr18Ni9Ti钎焊接头界面组织与结构

以Ag—Cu—Ti箔状钎料对钛合金TCA和不锈钢1Cr18Ni9Ti进行了真空钎焊。采用扫描电镜、能谱分析、金相显微镜和x一射线衍射等分析测试手段对钎焊过程中所形成的反应产物和接头界面结构进行了分析。结果表明：接头界面形成了Ti（s．s）、AS（s．s）、Ti—Cu金属问化合物等反应产物。连接温度较低（920℃）时,界面结构依次为1Cr18Ni9Ti／TiCu／Ag（s．s）＋少量Ti2cu／％2cu／Ti2cu＋Ti（s．s）／TC4;连接温度升高（960oC）时,界面结构为1Crl8Ni9Ti／Ti：Cu／Ti：Cu＋矩（s．s）／Ti2Cu／Ti2Cu＋Ti（s．s）／TCA;连接温度较高（1000oC）时,界面结构为1Crl8Ni9Ti／TiCu2／TiCu／Ti2Cu／Ti：Cu＋Ti（s．s）／TC4。提高钎焊温度与延长保温时间对钎焊接头界面组织结构有相似的影响,各反应相、反应层逐渐长大,金属问化合物反应相所占比例增大,而Ag（s．s）组织所占的比例变得更小,这种趋势随着焊接工艺参数的提高更加明显。     

Microstructural characterization of diamond/CBN grains steel braze joint interface using Cu–Sn–Ti active filler alloy

In order to develop the new generation superhard abrasive tools of diamond and cubic boron nitride (CBN), the brazing joint experiments of diamond/CBN crystals and AISI 1045 steel matrix using Cu–Sn–Ti active filler powder alloy were investigated in vacuum furnace. The brazing temperature was 930 °C and the dwelling time was 20 min. Interfacial characteristics of the brazing joint among the diamond/CBN grains, the active filler layer and the steel substrate were analyzed using scanning electron microscopy, energy dispersive spectroscopy and X-ray diffraction techniques. The results indicated that Ti element in the Cu–Sn–Ti alloys diffused preferentially to the surface of diamond/CBN grits to form a Ti-rich reaction layer in the brazed joints by microanalyses. Moreover, the TiC, TiN and TiB₂ phases in diamond/CBN interface and Cu–Ti phase in steel interface were confirmed by X-ray diffraction phase analysis. The wetting and bonding reactions on diamond/CBN by melting Cu–Sn–Ti alloy were realized through the interfacial reaction products like TiC, TiN and TiB₂ compounds during the brazing process. The adhesive strength experiments of the joint interfaces revealed that the grains were not pulled out from the bond interface. The reliable bonding strength of brazed diamond/CBN grains to the steel substrate can meet the application requirements of high efficiency machining in the industrial field.     

Ti-50Ni钎焊TZM与ZrCp-W接头界面组织及性能

采用Ti-50Ni(at%)钎料实现了TZM合金与ZrC_p-W复合材料的真空钎焊连接,通过SEM、EDS、XRD等方法分析了接头界面的微观组织结构,研究了钎焊温度对TZM/Ti-50Ni/ZrC_p-W接头界面组织及性能的影响。结果表明:钎焊接头的典型界面结构为TZM/Ti-Mo+TiNi_3+Mo-Ti-W/Ti Ni+TiNi_3+W(s,s)+(Ti,Zr)C/ZrC_p-W。随着钎焊温度的升高,Ti-Mo固溶体层宽度逐渐增大,线状条纹增多、增宽,组织逐渐粗大,晶界变圆滑;接头的抗剪强度随钎焊温度升高先升高后降低,当钎焊温度为1340℃,保温10 min时,接头获得最大抗剪强度为146 MPa。     

TiZrNiCu/Ti60润湿性及与TiBw-TC4钎焊研究

本文采用座滴法在真空下系统研究了硼含量对TiZrNiCu/Ti60润湿性的影响,且在940°C保温10分钟条件下实现了与的钎焊。通过SEM、XRD以及剪切实验研究了界面显微组织及剪切力学性能。添加B元素可以与Ti原位合成TiBw,从而细化界面的显微组织。当B含量为0.3 wt %时,TiBw-TC4 /TiZrNiCu-B/Ti60接头的最大剪切强度为177 MPa,比无B含量的接头强度高65%。然而,过量的B含量使TiZrNiCu-B在Ti60合金基体上产生大量的TiBw,导致润湿性恶化,在钎焊接头形成微孔和未焊合区域,从而使剪切强度下降。     

Ag-Cu钎料钎焊ZTA陶瓷与TC4钛合金

使用Ag-Cu钎料钎焊ZTA陶瓷与TC4钛合金,利用扫描电子显微镜(SEM)、能谱分析仪(EDS)和X射线衍射仪(XRD)等设备分析了钎焊接头界面组织,阐明了反应机理,并研究了钎焊温度对接头界面组织和力学性能的影响. 结果表明,钎焊接头的界面结构为ZTA陶瓷/TiO+Ti₃(Cu,Al)₃O/Ag(s,s)/Ti₂Cu₃/TiCu/Ti₂Cu/α+β-Ti/TC4合金. 随着钎焊温度的升高,钎缝中Ag基固溶体层变薄,Ti-Cu金属间化合物层变厚,当钎焊温度达到890 ℃时,Ti-Cu金属间化合物几乎占据整了个钎缝区域. 随着温度的升高,接头抗剪强度先增大后减小,在钎焊温度为890 ℃时,接头的室温抗剪强度达到最大值,其值为43.2 MPa.     

Interfacial features of TiAl alloy/316L stainless steel joint brazed with Zr−Cu−Ni−Al amorphous filler metal

TiAl alloy and 316L stainless steel were vacuum-brazed with Zr?50.0Cu?7.1Ni?7.1Al (at.%) amorphous filler metal. The influence of brazing time and temperature on the interfacial microstructure and shear strength of the resultant joints was investigated. The brazed seam consisted of three layers, including two diffusion layers and one residual filler metal layer. The typical microstructure of brazed TiAl alloy/316L stainless steel joint was TiAl alloy substrate/α₂-(Ti₃Al)/AlCuTi/residual filler metal/Cu₉Zr₁₁+Fe₂₃Zr₆/Laves-Fe₂Zr/α-(Fe,Cr)/316L stainless steel substrate. Discontinuous brittle Fe₂Zr layer formed near the interface between the residual filler metal layer and α-(Fe,Cr) layer. The maximum shear strength of brazed joints reached 129 MPa when brazed at 1020 °C for 10 min. The diffusion activation energies of α₂-(Ti₃Al) and α-(Fe,Cr) phases were ?195.769 and ?112.420 kJ/mol, respectively, the diffusion constants for these two phases were 3.639×10^?6 and 7.502×10^?10 μm²/s, respectively. Cracks initiated at Fe₂Zr layer and propagated into the residual filler metal layer during the shear test. The Laves-Fe₂Zr phase existing on the fracture surface suggested the brittle fracture mode of the brazed joints.     

Effects of Fabrication Parameters on Interface of Zirconia and Ti-6Al-4V Joints Using Zr55Cu30Al10Ni5 Amorphous Filler

ZrO₂ was brazed to Ti-6Al-4V using a Zr₅₅Cu₃₀Al₁₀Ni₅ (at.%) amorphous filler in a high vacuum at 1173-1273 K. The influences of brazing temperature, holding time, and cooling rate on the microstructure and shear strength of the joints were investigated. The interfacial microstructures can be characterized as ZrO₂/ZrO_2?x  + TiO/(Zr,Ti)₂(Cu,Ni)/(Zr,Ti)₂(Cu,Ni,Al)/acicular Widmanstäten structure/Ti-6Al-4V. With the increase in the brazing temperature, both the thickness of the ZrO_2?x  + TiO layer and the content of the (Zr,Ti)₂(Cu,Ni) phase decreased. However, the acicular Widmanstäten structure gradually increased. With the increase in the holding time, the (Zr,Ti)₂(Cu,Ni) phase decreased, and the thickness of the (Zr,Ti)₂(Cu,Ni) + (Zr,Ti)₂(Cu,Ni,Al) layer decreased. In addition, cracks formed adjacent to the ZrO₂ side under rapid cooling. The microstructures produced under various fabrication parameters directly influence the shear strength of the joints. When ZrO₂ and Ti-6Al-4V couples were brazed at 1173 K for 10 min and then cooled at a rate of 5 K/min, the maximum shear strength of 95 MPa was obtained.     

Cf/SiC复合材料与钛合金(Ti-Zr-Cu-Ni)+W复合钎焊分析

在适当的工艺参数下,用(Ti-Zr-Cu-Ni)+W复合钎料真空钎焊Cf/SiC复合材料与钛合金,采用SEM,EDS和XRD分析接头组织结构,利用剪切试验检测接头的力学性能.结果表明,钎焊时复合钎料中的钛、锆与Cf/SiC复合材料反应,在Cf/SiC复合材料与连接层界面生成Ti3SiC2,Ti5Si3和少量TiC(ZrC)化合物的混合反应层,在连接层与钛合金界面形成Ti-Cu化合物扩散层.增强相钨粉能有效缓解接头的残余热应力,提高接头力学性能,在连接温度930℃,保温时间20 min的工艺条件下,增强相钨粉含量为15%(体积分数)时,接头抗剪强度最高为166 MPa.     

Infrared brazing of TiAl intermetallic using BAg-8 braze alloy

TiAl intermetallic alloy joined by infrared brazing using BAg-8 braze alloy was investigated. The microstructural evolution of the brazed joint, shear strength and reaction kinetics across the joint was comprehensively evaluated. According to the experimental observations, silver would not react with the TiAl substrate, but copper reacted vigorously with the TiAl, forming continuous reaction layer. The consumption of copper from molten braze during infrared brazing resulted in depletion of the copper content from the braze. Therefore, chemical composition of the braze deviated from Ag-Cu eutectic into hypoeutectic with increased brazing time and/or temperature. Both AlCuTi and AlCu₂Ti phase were observed at the interface between BAg-8 and TiAl substrate for the specimen brazed at 950°C. By increasing the brazing temperature and time, the growth rate of AlCuTi phase was much faster than that of AlCu₂Ti phase. The maximum shear strength achieved 343 MPa for the specimen infrared brazed at 950°C for 60 s. Further increasing the brazing time resulted in excessive growth of brittle AlCuTi reaction layer, which greatly deteriorated the shear strength of the joint.     

Microstructure and shear strength of γ-TiAl/GH536 joints brazed with Ti−Zr−Cu−Ni−Fe−Co−Mo filler alloy

The influence of brazing temperature and brazing time on the microstructure and shear strength of γ-TiAl/GH536 joints brazed with Ti−Zr−Cu−Ni−Fe−Co−Mo filler was investigated using SEM, EDS, XRD and universal testing machine. Results show that all the brazed joints mainly consist of four reaction layers regardless of the brazing temperature and brazing time. The thickness of the brazed seam and the average shear strength of the joint increase firstly and then decrease with brazing temperature in the range of 1090−1170 °C and brazing time varying from 0 to 20 min. The maximum shear strength of 262 MPa is obtained at 1150 °C for 10 min. The brittle Al₃NiTi₂ and TiNi₃ intermetallics are the main controlling factors for the crack generation and deterioration of joint strength. The fracture surface is characterized as typical cleavage fracture and it mainly consists of massive brittle Al₃NiTi₂ intermetallics.     

Interfacial Behavior and Its Effect on Mechanical Properties of C<Subscript>f</Subscript>/SiC Composite/TiAl6V4 Joint Brazed with TiZrCuNi

In order to characterize the interfacial behavior of brazed joints and offer theoretical basis for the applications of TiZrCuNi-based composite fillers, C_f/SiC composite and TC4 were brazed by TiZrCuNi filler, and the microstructures of joints versus temperature and versus holding time were systematically studied in this paper. The mechanical properties of brazed joints were measured and analyzed. The results showed that Ti(Zr)C, Ti₅Si₃, Ti₂Cu, TiNi, TiZrCu₂, Ti₂(Cu,Ni) and Ti(s,s) were the predominant compounds in the joints. Brazing temperature had a distinct effect on the microstructures of joints: with the increase of brazing temperature, the structure of brazed joints was reduced from four parts to three parts, and the wavy reaction layer became continuous and much thicker. While holding time had a similar but weaker effect on microstructures: with the extension of holding time, the reaction layer became thicker, but it was difficult to induce the decrease in the structural parts of joint. The thickness of reaction layer determined the mechanical properties of joints. The results were beneficial for the selection of reinforced phases and the design of composite fillers to obtain better mechanical performances. When the brazing temperature was 940 °C and the holding time was 25 min, the maximum shear strength of brazed joints attained a value of 143.2 MPa.     

钛合金TC6与TC11高频感应钎焊工艺

以B-Ti57CuZrNi-S为钎料,在氩气保护气氛下对TC6/TC11钛合金进行高频感应钎焊工艺实验研究。采用光学显微镜(OM)、扫描电镜(SEM)及能谱分析(EDS)等测试方法,分析气体保护流量、流态以及工艺参数对焊接界面形貌、接头组织及元素分布的影响,并测试接头的抗拉强度。结果表明,钎焊界面主要由富Ti的β-Ti固溶组织和Cu-Ti、Ni-Ti以及(Cu,Ni)Ti/Zr组成的金属间化合物相组成。钎焊接头的抗拉强度随钎焊温度的升高或保温时间的延长,呈现先升高后降低的趋势,接头最高强度可达433MPa。TC6/TC11钛合金高频感应钎焊优化工艺参数带为:焊接温度910℃~930℃,保温时间120~150 s,Ar气保护流量1 MPa。     

Microstructure and mechanical properties of ZrB2–SiC ultrahigh temperature ceramic composite joint using TiZrNiCu filler metal

Abstract

ZrB₂–SiC ceramic composite was brazed by using TiZrNiCu active filler metal. The microstructure and interfacial phenomena of the joints were analysed by means of SEM, energy dispersive X-ray spectroscopy and X-ray diffraction. The joining effect was evaluated by shear strength. The results showed that the reaction products of the ZrB₂–SiC ceramic composite joint were TiC, ZrC, Ti₅Si₃, Zr₂Si, Zr(s,s) and (Ti, Zr)₂ (Ni, Cu), and the microstructure was separately ZrB₂–SiC/Zr(s,s)/Ti₅Si₃+Zr₂Si+TiC+ZrC+(Ti,Zr)₂(Ni,Cu)/Zr(s,s)/ZrB₂–SiC. A conceptual interface evolution model was established to explain the interface evolution mechanism. The maximum shear strength of the brazed joints was 143·5 MPa at the brazing temperature T of 920°C and the holding time t of 10 min.     

AgCuNiLi钎焊TiC金属陶瓷与GH3128界面结构及接头性能

采用AgCuNiLi钎料对TiC金属陶瓷与GH3128镍基高温合金进行钎焊。结果表明:当钎焊温度为840℃,保温10min时,接头典型界面结构可以表示为:TiC金属陶瓷/(Cu,Ni)/Ag(s.s)+Cu(s.s)/(Cu,Ni)/GH3128。随着钎焊温度的升高或保温时间的延长,TiC金属陶瓷附近的(Cu,Ni)固溶体层厚度增大,且向钎料内部呈树枝状长大,钎料内部的Ag-Cu共晶组织逐渐减少。界面机理分析表明:钎料中Li的加入能促进界面上(Cu,Ni)固溶体的形成;但(Cu,Ni)固溶体的继续长大则受钎料中Cu元素的扩散程度控制。当加热温度由810℃升高到960℃,接头抗剪强度呈现先增大,然后缓慢减小的变化趋势。当加热温度为880℃、保温时间为10min时,接头抗剪强度达到最大值204MPa。     

TiAl/Ni基合金反应钎焊接头的微观组织及剪切强度(英文)

以Ti为中间层,对TiAl基金属间化合物与Ni基高温合金进行反应钎焊连接,研究反应钎焊接头的界面微观结构及剪切强度。通过实验发现,熔融中间层与两侧母材反应剧烈,生成连续的界面反应层。典型的界面微观结构为GH99/(Ni,Cr)ss(γ)/TiNi(β2)+TiNi2Al(τ4)+Ti2Ni(δ)/δ+Ti3Al(α2)+Al3NiTi2(τ3)/α2+τ3/TiAl。当钎焊温度为1000°C,保温时间10min时,所得接头的剪切强度最高为258MPa。进一步升高钎焊温度或延长保温时间,会引起钎缝组织中组成相粗化和脆性金属间化合物层的生成,从而导致接头剪切强度的降低。     

Microstructure and mechanical performance of brazed joints of Cf/SiC composite and Ti alloy using Ag–Cu–Ti–W

Abstract

C_f/SiC composite was brazed to Ti alloy using interlayer of Ag–Cu–Ti–W mixed powder. The effects of W content and brazing parameters on the microstructure and properties of the brazed joints were investigated. The results show that W grains mainly distribute in Ag phase in the brazing layer and provide the effects of reinforcement and lowering residual thermal stress on the joint. The room temperature and 500°C shear strengths of the joints performed at 500°C for 30 min with Ag–Cu–Ti–50W (vol.-%) are remarkably higher than the optimal strengths of the joints brazed with Ag–Cu–Ti.