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.     

Compressive Strength Evaluation in Brazed ZrO<Subscript>2</Subscript>/Ti6Al4V Joints Using Finite Element Analysis

This study aims to synthesize and evaluate the compressive strength of the ZrO₂/Ti-6Al-4V joint brazed using an active metal filler Ag-Cu-Sn-Ti, and its application to dental implants assuring its reliability to resist the compressive failure in the actual oral environment. The brazing was performed at a temperature of 750 °C for 30 min in a vacuum furnace under 5 × 10^?6 Torr atmosphere. The microstructure of the brazed joint showed the presence of an Ag-rich matrix and a Cu-rich phase, and Cu-Ti intermetallic compounds were observed along the Ti-6Al-4V bonded interface. The compressive strength of the brazed ZrO₂/Ti-6Al-4V joint was measured by EN ISO 14801 standard test method. The measured compressive strength of the joint was ~1477 MPa—a value almost five times that of existing dental cements. Finite element analysis also confirmed the high von Mises stress values. The compressive strains in the samples were found concentrated near the Ti-6Al-4V position, matching with the position of the real fractured sample. These results suggest extremely significant compressive strength in ZrO₂/Ti-6Al-4V joints using the Ag-Cu-Sn-Ti filler. It is believed that a highly reliable dental implant can be processed and designed using the results of this study.     

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.     

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。     

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.     

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.     

Ni-34Ti钎料钎焊TiAl合金接头界面结构及性能

采用Ni-34Ti共晶钎料实现了TiAl合金的钎焊连接,分析了TiAl合金钎焊接头的界面结构,重点研究了钎焊温度对接头组织及性能的影响规律.结果表明,Ni-34Ti共晶钎料主要由TiNi相和TiNi3相组成,钎料熔点为1 120 ℃.不同钎焊温度下获得的接头界面组织均呈现对称特征,无气孔和裂纹等缺陷,接头中主要形成了TiNiAl2,B2,TiNiAl和TiNi2Al四种物相.Al元素在钎缝中的快速扩散,促进了钎缝中Ti-Ni-Al三元化合物的形成.钎焊温度为1 180 ℃保温10 min条件下,TiAl合金接头获得了最大的室温抗剪强度87 MPa.剪切过程中,裂纹容易在富含TiNi2Al相的区域产生和扩展,大量脆性TiNi2Al相的存在对接头的性能是有害的.     

Ti-22Al-25Nb合金板材的钎焊工艺

采用试验手段研究了Ti-22Al-25Nb合金板材的钎焊工艺. 结果表明,当钎焊温度为960 ℃时,Ti₂AlNb合金板材组织中短棒状O相组织发生少量溶解、块状O相组织的晶粒尺寸普遍增大,基体晶粒略粗化,但未出现相转变;随保温时间由15,30和60 min逐渐延长, Ti₂AlNb合金板材室温强度由1 257 MPa减少到1 000~1 100 MPa,但塑性不断提高,室温断后伸长率平均值由2.9%依次提高至3.4%,5.8%及5.0%. 确定出Ti₂AlNb合金板材的钎焊工艺参数为960 ℃/30 min/炉冷,此时相应接头抗剪强度较高,可达152 MPa.     

Low-melting-point titanium-base brazing alloys—part 2: Characteristics of brazing Ti-21Ni-14Cu on Ti-6Al-4v substrate

Filler metal of a low-melting-point (917 °C) Ti-21Ni-14Cu was brazed onto the substrate of Ti-6Al-4V alloy at 960 °C for 2,4, and 8 h to investigate the microstructural evolution and electrochemical characteristics of the brazed metal as a function of the period of brazing time. Optical microscopy, scanning and transmission electron microscopy, and x-ray diffractometry were used to characterize the microstructure and phase of the brazed metal; also, the potentiostat was used for corrosion study. Experimental results indicate that diffusion of copper and nickel from the filler metal into the equiaxed a plus intergranular β structure of Ti-6Al-4V substrate causes the lamellar Widmanstätten structure to form. The intermetallic Ti₂Ni phase existing in the prior filler metal diminishes, while the Ti₂Cu phase can be identified for the metal brazed at 960 °C for 2 h, but the latter phase decreases with time. Advantage might be taken from the evidence of faster diffusion of nickel than copper along the β phase to the substrate. In deaerated Hank’s solution, corrosion potential, corrosion current density, and critical potential for active-to-passive transition decrease while the passivation range broadens with the period of brazing time. However, all the brazed metals, immersed for different periods in oxygen-saturated Hank’s solution, show similar corrosion behavior, irrespective of the brazing time.     

钎焊时间对TZM合金与ZrCp-W复合材料接头界面组织及性能的影响

采用Ti-28Ni（质量分数,%）钎料在1 040℃实现了TZM合金与ZrC_p-W复合材料的真空钎焊连接,分析了钎焊时间对TZM合金与ZrC_p-W复合材料接头界面组织及力学性能的影响.结果表明,钎焊接头的典型界面结构为TZM/Ti（s,s）/Ti₂Ni/（Ti,Zr）C+W（s,s）/ZrC_p-W,钎缝宽度随保温时间的延长而增大,其中Ti（s,s）层的厚度没有变化,Ti₂Ni层厚度略有降低,而扩散层厚度随保温时间的延长稍有增加.当保温时间为10 min时,接头获得最大抗剪强度值120 MPa,接头断裂发生在TZM母材.     

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.     

Brazing of TiBw/TC4 composite and Ti60 alloy using TiZrNiCu amorphous filler alloy

TiB_w/TC4 composite was brazed to Ti60 alloy successfully using TiZrNiCu amorphous filler alloy, and the interfacial microstructures and mechanical properties were characterized by SEM, EDX, XRD and universal tensile testing machine. The typical interfacial microstructure was TiB_w/TC4 composite/β-Ti + TiB whiskers/(Ti, Zr)₂(Ni, Cu) intermetallic layer/β-Ti/Ti60 alloy when being brazed at 940 °C for 10 min. The interfacial microstructure evolution was influenced strongly by the diffusion and reaction between molten fillers and the substrates. Increasing brazing temperature decreased the thickness of brittle (Ti, Zr)₂(Ni, Cu) intermetallic layer, which disappeared finally when the brazing temperature exceeded 1020 °C. Fracture analyses indicated that cracks were initialized in the brittle intermetallic layer when (Ti, Zr)₂(Ni, Cu) phase existed in the brazing seam. The maximum average shear strength of joints reached 368.6 MPa when brazing was conducted at 1020 °C. Further increasing brazing temperature to 1060 °C, the shear strength was decreased due to the formation of coarse lamellar (α+β)-Ti structure.     

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。     

一种新型钛基钎料合金对γ-TiAl合金的钎焊性

在钎焊温度范围为1050 ~ 1125 ℃下保温10 min,采用非晶Ti-Zr-Cu-Ni-Co-Mo钎料成功地实现了Ti-47Al-2Nb-2Cr-0.15B (原子分数,%)合金钎焊连接. 运用SEM,EDS,XRD,TEM和维氏硬度仪等分析研究了铸态和箔带钎料显微组织、温度(900 ~ 1125 ℃)和保温时间(0 ~ 15 min)对铸态钎料在TiAl基合金表面上润湿铺展面积的影响,以及钎焊接头中界面显微组织和维氏硬度在不同钎焊温度下的变化规律. 结果表明,随着温度和保温时间的增加,铸态钎料在TiAl合金母材表面润湿铺展面积的增幅先增大后减小. 钎焊接头界面组织主要包括TiAl母材层,α₂-Ti₃Al+AlCuTi (层Ⅰ)和γ-(Ti, Zr)₂(Ni, Cu)+α-(Ti, Zr)(层Ⅱ). 钎缝中各区域的硬度均随着钎焊温度的增加而增加,1125 ℃时获得最大值为872(±8) HV,主要与钎缝中生成的硬脆金属间化合物(Ti, Zr)₂(Ni, Cu)和α₂-Ti₃Al有关.     

铝/钛异种合金激光熔钎焊接头特性

以C02激光为热源，以A1Si12焊丝为填充材料，对Ti-6Al-4V钛合金和5056铝合金异种材料激光熔钎焊进行研究，采用SEM、EDS、XRD和金相显微镜分析接头的微观结构特征，通过拉伸实验评定接头的力学性能。研究结果表明：所得接头具有熔焊和钎焊双重性质，即铝母材局部熔化，为熔化焊，而钛母材与焊缝金属之间存在金属间化合物层钎焊界面；钎焊界面上部的金属间化合物层组成复杂，可分为2层，即呈针状或芽状的Ti-Al-Si系金属间化合物层和以Ti-Al系金属间化合物为主的连续层；钎焊界面下部的金属间化合物层较薄；拉伸试样断裂倾向于发生在紧邻钎焊界面的焊缝上，平均抗拉强度为298．5MPa。     

Brazing of 6061 aluminum alloy/Ti-6Al-4V using Al-Si-Cu-Ge filler metals

Al-8.4Si-20Cu-10Ge and mixed rare-earth elements (Re) containing Al-8.4Si-20Cu-10Ge-0.1Re filler metals were used for brazing of 6061 aluminum alloy/Ti-6Al-4V. The addition of 20 wt.% copper and 10 wt.% germanium into the Al-12Si filler metal lowered the solidus temperature from 586 °C to 489 °C and the liquidus temperature from 592 °C to 513 °C. The addition of 0.1 wt.% rare-earth elements into Al-8.4Si-20Cu-10Ge alloy caused remarkable Al-rich phase refinement and transformed the needle-like Al₂Cu intermetallic compounds into block-like shapes. Shear strengths of the 6061 aluminum alloy/Ti-6Al-4V joints with the two brazing filler metals, Al-8.4Si-20Cu-10Ge and Al-8.4Si-20Cu-10Ge-0.1Re, varied insignificantly with brazing periods of 10-60 min. The average shear strength of the 6061 aluminum alloy/Ti-6Al-4V joints brazed with Al-8.4Si-20Cu-10Ge at 530 °C was about 20 MPa. Rare-earth elements appeared to improve the reaction of the Al-8.4Si-20Cu-10Ge filler metal with Ti-6Al-4V. The joint shear strength of the 6061 aluminum alloy/Ti-6Al-4V with Al-8.4Si-20Cu-10Ge-0.1Re reached about 51 MPa.     

The Joint Strength and Fracture Mechanisms of TC4/TC4 and TA0/TA0 Brazed with Ti-25Cu-15Ni Braze Alloy

In this paper, Ti-25Cu-15Ni (mass ratio) braze alloys were prepared by vacuum arc melting. Additionally, the TA0 pure titanium and TC4 titanium alloy were brazed with the Ti-25Cu-15Ni braze alloy at 960, 980, 1000, 1020, and 1040 °C. The effects of the braze temperature on the tensile strength of the TA0 and TC4 joints and their fracture mechanisms were studied. The maximum tensile strength of the TA0 joints of 219.9 ± 0.1 MPa was achieved at a brazing temperature of 980 °C, and the maximum tensile strength of the TC4 joints of 832.9 ± 0.1 MPa was achieved at the same brazing temperature. These results indicate that their ideal joint strength is comparable. According to the fractography results of the TA0 joints, a mixed fracture morphology is indicated. The TA0 fracture surface is dominated by cleavage fracture with a small contribution from ductile fracture. The TC4 joint fracture arises from cleavage.     

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.     

Al2O3/SUS304 Brazing via AgCuTi-W Composite as Active Filler

Alumina ceramic (α-Al₂O₃) was brazed to stainless steel (SUS304) using an Ag-Cu-Ti + W composite filler and a traditional active brazing filler alloy (CuSil-ABA). Then, the effects of the presence of W particles and of the brazing parameters on the microstructures and mechanical properties of the brazed joints were investigated. The maximum tensile strength of the joints obtained using Ag-Cu-Ti + W composite filler was 13.2 MPa, which is similar to that obtained using CuSil-ABA filler (13.5 MPa). When the joint was brazed at 930 °C for 30 min, the tensile strengths decreased for both kinds of fillers, although the strength was slightly higher for the Ag-Cu-Ti + W composite filler than for the Ag-Cu-Ti filler. The interfacial microstructure results show that the Ti reacts with W to form a Ti-W-O compound in the brazing alloy. When there are more W particles in the brazing alloy, the thickness of the Ti _X O _Y reaction layer near the alumina ceramic decreases. Moreover, W particles added to the brazing alloy can reduce the coefficient of thermal expansion of the brazing alloy, which results in lower residual stress between the Al₂O₃ and SUS304 in the brazing joints and thus yields higher tensile strengths as compared to those obtained using the CuSil-ABA brazing alloy.