TC4钛合金钎焊工艺与接头组织性能研究

TC4钛合金是一种中等强度的α-β型双相钛合金,具有优异的综合性能,长时间工作温度可达到400℃。文中针对TC4钛合金复杂精密构件设计制造可能的需求,采用Ti-21Cu-13Zr-9Ni钎料对TC4合金进行了真空钎焊。通过扫描电镜与能谱等手段,对钎焊接头界面的元素分布及钎焊接头的组织进行分析;同时测试了接头室温和高温力学性能。试验结果表明,采用Ti-21Cu-13Zr-9Ni钎料钎焊TC4钛合金合理可行;采用Ti-21Cu-13Zr-9Ni钎料930℃/10 min钎焊TC4钛合金的钎焊接头,通过930℃/40 min扩散处理后,钎焊接头室温、高温400℃和600℃抗拉强度分别达到930 MPa、610 MPa、400 MPa;基本等强于同一热循环的母材抗拉强度。采用Ti-21Cu-13Zr-9Ni钎料930℃/10 min钎焊TC4钛合金的钎焊接头,通过930℃/40 min扩散处理后,其钎焊接头的冲击性能有明显提高。     

TC4钛合金钎焊接头的组织与性能

采用Ti-37.5Zr-15Cu-10Ni钎料对TC4钛合金进行了钎焊,钎焊温度为900 ℃,保温时间分别为30、60和90 min。结果表明,在900 ℃时该钎料可润湿TC4母材,润湿角平均值为16.7°。保温时间为90 min时,钎焊界面中心处钎料元素已扩散得较充分,与钎料合金成分相比,Zr元素由37.5%降低至1.79%,Cu和Ni元素分别由15%和10%降低至1.66%和1.64%。TC4钛合金钎焊试样的室温抗拉强度平均值为1007.6 MPa,多数试样断于母材,属于微孔聚合机制导致的断裂失效。     

LaNd对Ti-13Zr-21Cu-9Ni钎料铺展性及TC4接头性能的影响

为了优化Ti-13Zr-21Cu-9Ni钎料性能、获得一种性能优良的Ti合金接头,向Ti-13Zr-21Cu-9Ni钎料中添加了稀土元素LaNd. 以应用普遍的TC4合金为母材,通过真空炉、场发射扫描电镜、X射线衍射仪等设备研究了稀土元素LaNd对Ti-13Zr-21Cu-9Ni钎料铺展性能及TC4接头性能的影响. 结果表明,随着LaNd添加量的增加,Ti-13Zr-21Cu-9Ni-xLaNd钎料的铺展面积和Ti-13Zr-21Cu-9Ni-xLaNd/TC4钎焊接头的抗剪强度先增大后减小. 当LaNd添加量为0.3%时,Ti-13Zr-21Cu-9Ni-xLaNd钎料铺展面积最大,最大值为0.74 cm2,较基体提高了88.8%;当LaNd添加量继续增加时,生成的Cu₅La相会使钎料的铺展性能大幅降低. Ti-13Zr-21Cu-9Ni-xLaNd/TC4钎焊接头抗剪强度在LaNd添加量为0.3%时达到最大值,为157.1 MPa,较基体提高了45.2%. LaNd的最佳添加量应该为0.3%.     

钛基钎料高温钎焊TZM界面行为及热稳定性研究（英文）

采用Ti-8.5Si、Ti-33Cr和Ti-30V-3Mo钎料实现了钛锆钼(TZM)合金的高温真空钎焊连接,借助SEM、EDS及润湿性试验和抗剪试验等分析方法,研究了钛基钎料高温钎焊TZM及钎焊接头经高温热循环后的热稳定性。结果表明,Ti-8.5Si、Ti-33Cr在1520oC/6min的工艺条件下良好润湿TZM,润湿角分别为10o和9o,Ti-8.5Si钎料的铺展面积大于Ti-33Cr钎料的铺展面积,Ti-30V-3Mo钎料在1680oC/8 min的条件下在TZM板上的润湿角为5°。Ti-8.5Si/TZM接头界面形成(Ti, Mo)固溶体,钎缝中心由(Ti, Mo)固溶体和Ti5Si3相组成。Ti-33Cr/TZM接头界面形成(Ti,Mo)固溶体,钎缝中心由(βTi,Cr)固溶体和αTi+(αTi+αTi Cr2)共晶组成。Ti-30V-3Mo/TZM接头,钎缝区主要由(βTi, V)固溶体和αTi组成,界面区由Ti与Mo形成(Ti,Mo)固溶体。3种钎料钎焊TZM,均形成固溶体钎焊接头而实现钎料与TZM的冶金结合,钎焊接头强度分别为135.8 MPa(Ti-8.5Si)、132 MPa(Ti-33Cr)和131 MPa(Ti-30V-3Mo)。Ti-8.5Si/TZM、Ti-33Cr/TZM接头经过1200oC/60min没有观察到明显的晶间渗入和母材溶蚀,界面固溶体结合形式无变化。Ti-30V-3Mo/TZM接头经过1550oC/60 min热循环后,观察到1个晶粒深度的晶间腐蚀,没有明显的母材溶蚀现象,且界面依然保持固溶体结合形式。3种钛基钎料可实现TZM的高温钎焊,依靠界面固溶体实现冶金结合,经高温长时间热循环后钎焊接头组织性能稳定,发生晶间渗入敏感性低,为TZM的高温应用连接提供理论与试验指导。     

铝硅合金钎焊Cf/Al复合材料的界面反应及连接机理

在500～570℃的温度范围内,采用Al-Si-Cu、Al-Si-Cu-Zn钎料,对碳纤维增强铝基复合材料(碳体积分数为50%)进行了高频感应钎焊.结果表明,钎料中的Si和Cu向母材扩散,复合材料中的碳纤维与渗入的液态钎料及基体Al发生界面反应,生成了Al4C3、SiC和CuAl2脆性化合物.连接接头具有较好的力学性能,使用Al-28Cu-6Si和Al-4Cu-10Si钎料,在无压、无钎剂状态下,钎焊接头的抗剪强度分别为63和75 MPa,剪切断裂发生在钎料层与母材界面上.     

Zr元素含量对钛基钎料合金固溶强化的影响

利用EET理论分析Zr元素对钛基钎料合金的固溶强化效果,得出锆含量自45%~12%变化时,Ti-Zr-15Cu-10Ni(质量分数,%)钎料合金晶胞内最大共价电子数先保持不变、而后减小再增大.当锆含量为37.5%时,Zr元素对钛基钎料合金的固溶强化作用相对较大,采用此锆含量的钎料合金Ti-37.5Zr-15Cu-10Ni(质量分数,%)对Ti₃Al-Nb合金进行同质过渡液相扩散连接.在连接温度低于1000℃条件下,钎料合金的扩散能力主要受保温时间的影响;在较高连接温度下,钎料合金的扩散能力明显提高,可在短时保温条件下形成组织均匀、无析出物的连接界面.     

钛基钎料高温钎焊TZM界面行为及热稳定性研究

采用Ti-8.5Si、Ti-33Cr和Ti-30V-3Mo钎料实现了钛锆钼(TZM)合金的高温真空钎焊连接,借助SEM、EDS及润湿性试验和抗剪试验等分析试验方法,研究了钛基钎料高温钎焊TZM及钎焊接头经高温热循环后的热稳定性。结果表明,Ti-8.5Si、Ti-33Cr在1520℃/6min的工艺条件下良好润湿TZM,润湿角分别为10°和9°,Ti-8.5Si钎料的铺展面积大于Ti-33Cr钎料的铺展面积,Ti-30V-3Mo钎料在1680℃/8min的条件下在TZM板上的润湿角为5°。Ti-8.5Si/TZM接头界面形成(Ti,Mo)固溶体,钎缝中心由(Ti,Mo)固溶体和Ti₅Si₃相组成。Ti-33Cr/TZM接头界面形成(Ti,Mo)固溶体,钎缝中心由(βTi,Cr)固溶体和αTi+(αTi+αTiCr₂)共晶组成。Ti-30V-3Mo/TZM接头,钎缝区主要由(βTi,V)固溶体和αTi组成,界面区由Ti与Mo形成(Ti,Mo)固溶体。三种钎料钎焊TZM,均形成固溶体钎焊接头而实现钎料与TZM的冶金结合,钎焊接头强度分别为135.8MPa(Ti-8.5Si)、132MPa(Ti-33Cr)和131MPa(Ti-30V-3Mo)。Ti-8.5Si/TZM、Ti-33Cr/TZM接头经过1200℃/60min没有观察到明显的晶间渗入和母材溶蚀,界面固溶体结合形式无变化。Ti-30V-3Mo/TZM接头经过1550℃/60min热循环后,观察到1个晶粒深度的晶间腐蚀,没有明显的母材溶蚀现象,且界面依然保持固溶体结合形式。三种钛基钎料可实现TZM的高温钎焊,依靠界面固溶体实现冶金结合,经高温长时间热循环后钎焊接头组织性能稳定,发生晶间渗入敏感性低,为TZM的高温应用连接提供理论与试验指导。     

关于铝钎焊冶金过程的一个问题

讨论了钎焊温度下铝钎焊钎缝的冶金过程:1.Al母材溶入钎料首先从晶界处开始,由于液态钎料的均匀化,Si渗入了晶界;2.液态钎料中的Si向母材Al晶粒中扩散形成α相。     

真空钎焊TiAl基合金用Ti-Zr-Cu-Ni-Co-Mo钎料的钎焊性能（英文）

采用非晶和晶态Ti-25Zr-12.5Cu-12.5Ni-3.0Co-2.0Mo(质量分数,%)钎料对Ti-47Al-2Nb-2Cr-0.15B(摩尔分数,%)合金进行真空钎焊连接,对两种钎料的熔化行为、润湿铺展性、填缝隙能力以及由钎焊TiAl基合金所得的钎焊接头进行详细的研究。结果表明:与晶态钎料相比,非晶钎料具有更窄的熔化温度区间、更低的液相线温度和熔化激活能;同时,非晶钎料在Ti-47Al-2Nb-2Cr-0.15B合金表面上具有更优异的钎焊性。非晶和晶态两种钎料的钎焊接头均由两侧的界面反应层和中心钎焊层组成,非晶钎料钎焊接头的抗拉强度均高于相同钎焊工艺参数下的晶态钎料钎焊接头的抗拉强度,且在钎焊温度1273K下获得的钎焊接头的抗拉强度达到最大值254 MPa。     

A PROBLEM ON METALLURGICAL PROCESS DURING ALUMINUM BRAZING——Wish to Discuss with Mr. CHEN Genbao and Others

讨论了钎焊温度下铝钎焊钎缝的冶金过程:1.Al母材溶入钎料首先从晶界处开始,由于液态钎料的均匀化,Si渗入了晶界;2.液态钎料中的Si向母材Al晶粒中扩散形成α相。     

TC4钛合金/304不锈钢异种材料蜂窝结构钎焊工艺

采用Ti-37.5Zr-15Cu-10Ni和Ag-28Cu两种钎料分别对TC4钛合金面板/304不锈钢蜂窝芯异种材料蜂窝结构进行了钎焊,对钎焊界面组织和蜂窝结构的力学性能进行了对比分析. 结果表明,Ti基钎料与304不锈钢蜂窝芯箔材界面润湿反应性能较差且Ti基钎料钎缝显微硬度较高,导致钎焊界面强度低,蜂窝拉伸力学性能差. Ag基钎料与304不锈钢蜂窝芯箔材和TC4面板均发生显著的界面反应,钎焊温度830 ℃,保温时间10 min时,蜂窝抗拉强度为10.35 MPa,呈蜂窝芯破坏特征. Ag基钎料蜂窝抗拉强度明显优于Ti基钎料结果,适用于TC4钛合金面板/304不锈钢蜂窝芯异种材料蜂窝钎焊.     

Interfacial Microstructure Evolution and Shear Strength of Titanium Sandwich Structures Fabricated by Brazing

The corrugated sandwich structure, consisting of a CP Ti (commercially pure titanium) core between two Ti-6Al-4V face sheets, was brazed using pasty Ti-37.5Zr-15Cu-10Ni as filler alloy, at the temperature of 870°C for 5, 10, 20, and 30 min. The effect of brazing time on the microstructure and elemental distribution of the brazed joints was examined by means of SEM, EDS, and XRD analyses. It was found that various intermetallic phases were formed in the brazed joints, following a brazing time of 5 min, and their contents were decreased by the increment of brazing time, while prolonged brazing time resulted in a fine, acicular Widmanstätten microstructure throughout the entire joint. In addition, shear testing was performed in the brazed corrugated specimens in order to indirectly assess the quality of the joints. The debonding between CP Ti and Ti-6Al-4V was observed in the specimen brazed for 5 min and the fracture of the CP Ti corrugated core occurred after 30 min of brazing time. Additionally, when brazed for 10 min or 20 min, brittle intermetallic compounds in the joints and the grain growth of the base metal were controllable. Therefore, the sandwich structures failed without debonding in the joints or fracture within the base metal, demonstrating a good combination of strength and ductility.     

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.     

钎焊温度对TC4与Ti3Al-Nb合金钎焊接头组织的影响

采用50Ti-20Zr-20Ni-10Cu粉末钎料对Ti3Al-Nb合金与TC4合金进行真空钎焊,通过SEM、EDS、电子探针及拉伸试验研究不同钎焊温度下钎焊接头的显微组织及性能特征.结果表明,钎焊温度升高钎焊接头强度并不提高;不同温度下钎焊接头中靠近TC4合金基体边界处均生成魏氏体组织,随温度升高魏氏体组织粗化程度加剧;整个钎焊接头中Ti3Al-Nb合金基体与钎料的反应程度弱于TC4合金基体.     

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.     

Low-melting-point titanium-base brazing alloys—part 1: Characteristics of two-, three-, and four-component filler metals

The melting point, microstructure, phase, and electrochemical behavior of Ti-21Ni-15Cu alloy, together with two-, three-, and four-component low-melting-point titanium-base brazing alloys, are presented in this paper. Five filler metals were selected for the study, in which melting points were measured by differential thermal analysis, phases identified by x-ray diffractometry, and corrosion behaviors tested by potentiodynamic polarization. The experimental results show that the three-component Ti-15Cu-15Ni and the newly developed Ti-21Ni-14Cu alloys exhibit the combination of lower melting point and superior corrosion resistance compared to the two-and four-component titanium alloys, 316L stainless steel, and a Co-Cr-Mo alloy in Hank’s solution at 37 °C. On a short time basis, the presence of Ti₂Ni and Ti₂Cu intermetallics in the Ti-15Cu-15Ni and Ti-21Ni-14Cu alloys should not be preferentially dissolved in galvanic corrosion with respect to the dissimilar Ti-6Al-4V alloy.     

Vacuum brazing Mo using Ti-Ni-Nb braze alloys

A novel approach of brazing Mo using three clad Ti-Ni-Nb foils, 40Ti-35Ni-25Nb, 50Ti-35Ni-15Nb and 60Ti-15Ni-25Nb in wt.%, has been performed in the experiment. Similar microstructural evolution of the joint is observed for three foils. The joint using 60Ti-25Ni-15Nb foil brazed at 1250 °C for 600 s demonstrates the highest bending strength of 526 MPa. The clad Ti-Ni-Nb foils show potential in brazing Mo for industrial application.     

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。