SiC/SiC-哈氏合金异质连接机制及其氟熔盐腐蚀特性分析（英文）

以Cu-2.67Ni钎料,采用钎焊工艺获得了SiC/SiC复合材料-哈氏合金异质接头,并研究了其在800℃的FLiNaK熔盐中的腐蚀行为。利用不同手段表征了接头微观结构和氟熔盐腐蚀行为。结果表明, Ni、Cr、Mo等合金元素以及SiC中的Si元素发生互扩散。Cr元素替代Ni元素,在焊料–复合材料界面富集并形成不连续碳化物层。高温钎焊加速Ni扩散并侵蚀SiC,低温钎焊导致焊料熔融不充分。钎焊过程中的元素扩散改变了哈氏合金的组成,导致其耐腐蚀性能恶化。Cr与Si的选择性溶出导致钎焊接头及合金的腐蚀损伤,这与热力学计算结果一致。     

SiC陶瓷真空钎焊接头显微组织和性能

在高真空条件下采用Ti-35Zr-35Ni-15Cu(质量分数/%)钎料对SiC陶瓷进行了钎焊连接,研究了接头界面组织的形成过程以及工艺参数对接头性能的影响。结果表明:钎料与SiC陶瓷发生了复杂的界面反应,生成了多种界面产物。当钎焊温度为960℃,保温时间为10min时,SiC陶瓷侧形成了连续的TiC和Ti5Si3+Zr2Si层,同时Ti5Si3+Zr2Si向钎缝中心生长呈长条状。SiC陶瓷到接头钎缝中心的显微组织依次为:SiC/TiC/Ti5Si3+Zr2Si/Zr(s,s)/Ti(s,s)+Ti2(Cu,Ni)/(Ti,Zr)(Ni,Cu)。钎焊温度为960℃,保温时间为30min时,长条状的Ti5Si3+Zr2Si贯穿了整个接头。钎焊接头强度随着钎焊温度的升高和钎焊时间的延长都呈现先增大后减小的趋势。当钎焊温度为960℃,保温时间为10min时,接头的剪切强度最高,达到了110MPa。     

高体积比SiCp/A356复合材料真空扩散钎焊接头组织与性能研究

采用快速甩带技术制备了7组(Al-33.3Cu-6.0Mg)-xNi(x=0,0.5,1.0,2.0,3.0,4.0,5.0,质量分数/%)急冷箔状钎料,分别对化学镀Ni-P合金前后的SiCp/A356复合材料进行真空扩散钎焊。通过剪切实验对钎焊接头的抗剪强度进行测定,并利用扫描电镜和能谱分析等方法对接头微观组织进行观察和分析。结果表明,当向Al-33.3Cu-6.0Mg钎料合金中添加不同含量的Ni时,其急冷钎料的固-液相线(504~522℃)变化较小;当w(Ni)=3%且在570℃、保温30min的钎焊工艺下,A356基体/钎料两界面间发生适当的互扩散和溶解现象(585℃时出现溶蚀缺欠),且部分钎料/SiC颗粒的接触界面发生Mg参与的化学反应,接头抗剪强度达到64.97 MPa;而在同种钎焊工艺下,对于化学镀Ni-P合金镀层后的SiCp/A356复合材料,其接头处A356基体/Ni-P合金镀层/钎料等接触界面易于形成富含Al、Ni的致密反应层,接头连接质量显著提高,且w(Ni)=4%时,接头抗剪强度达到79.96 MPa。     

层状结构TiAl合金钎焊组织及性能

目的揭示层状结构Ti Al合金薄板采用钎料Ti-Zr-Cu-Ni时,在钎焊过程中的扩散行为,以及钎焊后的组织和力学性能。方法对焊缝及周边区域进行电子扫描(SEM)、能谱分析(EDS)、X射线衍射分析(XRD),明确钎焊过程中的扩散行为以及钎焊接头组织;对钎焊后的层状Ti Al合金进行剪切试验和纳米压痕试验,评价焊缝的力学性能。结果采用Ti-Zr-Cu-Ni钎箔钎焊Ti Al合金板材,Al元素为主要扩散元素,从母材向焊缝进行扩散,在Ti Al合金与钎料界面处生成Ti_3Al金属化合物,在焊缝处生成(Ti,Zr)_2(Cu,Ni)(s,s),Ti_2(Cu,Ni)(s,s),(Ti,Zr)_2Ni(s,s)和α-Ti。焊后接头的剪切强度为252 MPa,裂纹在母材处生成,穿过焊缝扩展到另一侧母材区域发生断裂,焊缝区硬度值高于母材,为12.8 GPa。结论选用Ti-Zr-Cu-Ni钎料在930℃下进行钎焊,能够获得质量良好的接头。     

电流辅助下CoFeCrNiCuTi2高熵合金钎焊SiC陶瓷接头组织与性能

采用电流辅助连接技术，以CoFeCrNiCuTi₂高熵合金为连接层材料，在1125℃的温度下，实现了SiC陶瓷的快速钎焊，提高了连接效率的同时保证了元素的充分扩散，系统研究了钎焊温度对连接接头界面微观结构和力学性能的影响。结果表明：所获得的钎焊接头无明显缺陷，焊缝组织主要由高熵FCC相、TiC相、Cr₂₃C₆相组成。界面致密的TiC反应层的形成在一定程度上抑制了高熵合金的分解和金属间化合物的生成，并缓解了SiC基体界面与高熵合金钎料之间的热应力。同时，由于高熵合金钎料的迟滞扩散效应，焊缝中心主体钎料仍保持高熵合金的FCC结构。力学性能测试表明：钎焊接头强度随钎焊温度升高呈先降低后增大的变化趋势。当连接温度为1125℃时，碳化硅接头获得最大弯曲强度，达到37 MPa,高于普通镍基钎料约21.3 MPa。     

SiC陶瓷真空钎焊接头的组织及性能分析

采用BNi-5钎料对SiC陶瓷进行真空钎焊,获得了力学性能良好的SiC钎焊接头,并对焊缝的微观结构和形成过程进行了分析。研究结果表明,Ni基钎料与SiC母材发生反应生成层状界面反应层结构,所形成的SiC钎焊接头钎缝微观形貌可以表述为:SiC母材/石墨+Ni_2Si/Ni_2Si/石墨+Ni_2Si/Cr_3Ni_2SiC/Ni+Cr_3Ni_5Si_2/Cr_3Ni_2SiC/石墨+Ni_2Si/Ni_2Si/石墨+Ni_2Si/SiC母材。所得SiC钎焊接头常温力学性能较好,平均钎焊接头剪切强度可达到124 MPa。Ni基钎料钎焊SiC陶瓷接头的断裂位置位于钎料与陶瓷基体间的界面反应层,主要原因是界面反应层中Ni_2Si和Cr_3Ni_2SiC等脆性化合物在钎焊接头拉伸变形过程中会产生应力集中,在残余钎焊应力的共同作用下钎焊接头发生断裂。     

Ti-61Ni真空钎焊TZM合金接头界面组织与力学性能

目的 研究不同钎焊温度下获得TZM/Ti-61Ni/TZM接头的微观组织演化及力学性能的变化,为获得可靠钎焊接头提供指导.方法 采用电弧熔炼方法制备Ti-61Ni,将以TZM/Ti-61Ni/TZM"三明治"结构装配的试样放入真空炉中进行不同温度(1200～1280℃)下的钎焊连接,利用SEM和EDS等手段分析钎料与母材之间的相互作用,测试接头的力学性能并分析接头断裂行为,研究温度对接头界面组织演化和力学性能的影响.结果 钎缝主要为TiNi相和TiNi3相,钎料中Ti元素向母材扩散形成Mo(s,s)扩散层;钎焊温度升高,钎缝宽度减小,TiNi相减少,钎料对TZM母材的溶蚀加剧;接头的抗剪强度先升高后下降,接头在TZM母材处断裂.结论 采用Ti-61Ni高温钎料实现了TZM合金的可靠连接,接头典型界面组织为TZM/扩散层(Mo(s,s))/TiNi+TiNi3/扩散层(Mo(s,s))/TZM;当钎焊温度为1240℃时,接头的抗剪强度达到最大值,为121 MPa.     

SiCf/SiC复合材料耐高温氟熔盐腐蚀性能研究

实验研究了熔渗(MI)工艺、浸渍-裂解(PIP)工艺和化学气相渗透(CVI)工艺制备SiC_f/SiC复合材料在800℃的氟熔盐(46.5mol% LiF-11.5mol% NaF-42.0mol% KF)中的腐蚀行为, 通过X射线衍射仪、扫描电镜以及能谱仪等表征手段, 对腐蚀前后样品的物相组成和微观结构进行了分析。实验结果表明, 不同工艺获得的SiC基体与高温氟熔盐的相容性与基体组成有关; MI-SiC中的游离Si相以及PIP-SiC和CVI-SiC中的富氧相是SiC基体中的两种腐蚀弱区, 易被熔盐选择性腐蚀; MI-SiC_f/SiC复合材料以纤维束间游离Si基体腐蚀为主, PIP-SiC_f/SiC复合材料基体腐蚀损伤集中在网络状富氧带, CVI-SiC_f/SiC复合材料的腐蚀损伤主要是沉积层间的含氧边界以及由此造成的基体层状剥离。与MI和PIP样品相比, CVI基体纯度高, 结晶度好, 表观腐蚀速率仅为0.0445 μg/(mm²·h), 具有更好的耐氟熔盐腐蚀性能。     

镍基钎料钎焊GH586高温合金

采用非晶箔状BNi82CrSiB和BNi81CrB钎料以不同的保温时间进行钎焊实验,对钎焊接头进行了力学性能测试。利用扫描电镜和能谱分析对钎焊接头微观组织和断口进行观察和分析。结果表明,在钎焊温度下延长钎焊时间(60min)能够促进钎缝与扩散层的元素均匀分布,提高钎焊接头的室温和高温(930℃)拉伸性能。通过调整钎料合金成分,提高了钎焊接头的拉伸性能,高温拉伸性能提高22.5%。接头断裂发生在近缝区基体一侧,断裂形式主要为沿晶断裂。同时讨论了Si,B等元素对钎焊接头的组织和性能的影响。     

铝钎焊接头中Cu元素的扩散行为研究

为了研究Al-Cu共晶合金钎料中Cu元素在钎焊接头中的扩散行为,采用快速凝固技术制备了Al-Cu共晶合金钎料,以纯铝棒料为基体采用对接接头在不同温度下进行了真空钎焊,并利用SEM和EDS对接头进行了研究.研究表明:钎料中Cu原子的扩散以晶界扩散为主,当晶界上Cu原子的浓度达到一定值后开始向晶内扩散,当晶内的Cu原子饱和后又反向扩散到晶界上;钎焊温度过低、保温时间过短时,Cu元素在基体内部不能充分扩散,在基体晶界上产生严重偏析,生成Al-Cu相中最脆的θ相(Al2Cu);提高钎焊温度和保温时间有利于提高Cu元素在Al基体中的扩散,但过高的钎焊温度又导致θ相的重新出现,选取合适的钎焊工艺参数才能获得良好的钎缝.     

22Ti-78Si高温共晶钎料对SiC陶瓷的钎焊连接

利用非自耗电弧熔融技术制备的22Ti-78Si (wt%)高温共晶钎料实现SiC陶瓷连接. 采用SEM、材料试验机研究了工艺参数对钎焊接头的组织结构、强度和断口形貌的影响规律. 结果表明: 在钎焊温度1380~1420℃、保温时间5~20min、钎料厚度50~200 μm条件下, 均能实现SiC陶瓷连接, 在1400℃、保温时间10min和钎料厚度100μm的条件下, SiC/22Ti-78Si/SiC接头剪切强度最大值可达125MPa.     

Brazing of SiC to a wrought nickel-based superalloy using CoFeNi(Si, B)CrTi filler metal

Newly-developed CoFeNi(Si, B)CrTi brazing filler metal was used for joining of SiC to a wrought nickel-based superalloy (GH3044). The brazing alloy was fabricated into brazing foils by a rapid solidifying technique, and the brazing temperature was fixed at 1150 °C. The SiC/GH3044 joints using single interlayer Ni or triple interlayers of Ni/W/Ni showed very low strength, and this was because the Ni severely interfered with the normal reactions between the SiC and the brazing alloy. When using triple interlayers of Kovar/W/Ni for the SiC/GH3044 joining, the joint strength was remarkably elevated to 62.5-64.6 MPa. Kovar has a low coefficient of thermal expansion. Moreover, when Kovar was used as an interlayer neighboured to the brazed SiC, it basically ensured the normal interfacial reactions between the brazed SiC and the used brazing alloy. These two factors should account for the improvement of the joint strength.     

SiC陶瓷与Ti合金的(Ag-Cu-Ti) -W复合钎焊接头组织结构研究

研究了在Ag,Cu,Ti粉末中加入W粉连接钛合金和SiC陶瓷的接头组织结构和接头状况.结果表明W颗粒均匀分布在钎缝的Ag相中,且未与Ag-Cu-Ti合金基体发生冶金反应,W颗粒的大小和形状基本上与加入前的粉末相当.在较低的钎焊温度和较短的钎焊时间下,能形成组织结构均匀、连接良好的复合接头,钎缝内Cu-Ti相较少,钎缝与钛合金界面形成了多层Ti含量呈梯度变化的Cu-Ti扩散反应层组成的扩散带.W的加入降低了接头热应力.而较高的钎焊温度和较长的钎焊时间,容易在近缝区的陶瓷中产生裂纹.由于扩散进入钎缝Ti量的增多,使得钎缝内形成很多长条形CuTi相组织,提高了与钎缝相邻的Cu-Ti扩散反应层的Ti浓度,并且钎缝内钛合金界面附近形成了没有W相的带状区域.     

CuTiNiZrV Amorphous Alloy Foils for Vacuum Brazing of TiAl Alloy to 40Cr Steel

Vacuum brazing of TiAl alloy to 40Cr steel sheets was conducted with newly developed CuTiNiZrV amorphous foils. It was found that a diffusion layer,filler metal and reaction layer existed in the brazed seam. The diffusion layer in the joint brazed with Cu43.75Ti37.5Ni6.25Zr6.25V6.25(at.%) foil was flat and thin,containing Ti19Al6 and Ti2Cu intermetallic compounds; however,the diffusion layer brazed with Cu37.5Ti25Ni12.5Zr12.5V12.5 foil was uneven with bulges,consisting of essentially Ti-based solute solution. The foil with 12.5 at.% V showed inferior spreadability compared to that with 6.25 at.% V at brazing temperature. However,fracture happened along the diffusion layer with 6.25 at.% V foil due to the formation of brittle intermetallic phases,but the joints brazed with 12.5 at.% V foil failed through the TiAl substrate. These results show that designing amorphous alloy with less Ti and more V for brazing TiAl alloy to steel is appropriate.     

铝合金熔体氧化制备Al2O3 / SiC/ Ni/ Al-Si多相模糊界面陶瓷基复合材料

针对Al₂O₃ / Al 复合材料中金属相Al 对其高温性能的不利影响, 本试验在高温下将铝合金熔体氧化渗透到注浆成型的SiC/ Ni 多孔预制体中, 制备了Al₂O₃ / SiC/ Ni/ Al-Si 多相陶瓷基复合材料。借助光学显微镜、电子显微镜(SEM) 、X 射线衍射仪(XRD) 、波谱仪( EDS) 等手段分析了预制体和复合材料的相组成、微观结构及界面特征。结果表明, 复合材料的主晶相为Al₂O₃ 与SiC , 相间存在Al (Si) 复合氧化物、NiAl₂O₄ 及Ni 与Al-Si 合金相, 各相界面处成分呈连续过渡变化趋势, 构筑了具有模糊界面特征的多相复合材料。      

高体积比SiCp/6063Al复合材料的铝基钎料制备及钎焊工艺研究

采用快速甩带技术制备了(Al-10Si-20Cu-0.05Ce)-1Ti(质量分数/％)急冷箔状钎料,并对60％体积分数的SiCp/6063Al复合材料进行真空钎焊实验,然后对钎料及接头的显微组织与性能进行测定和分析.结果表明,急冷钎料的微观组织细小、成分均匀,厚80～90μm,主要包含Al、CuAl2、Si和Al2Ti等相.当升高钎焊温度(T/℃)或延长保温时间(t/min),SiCp/钎料界面的润湿性改善,6063Al基体/钎料间互扩散和溶解作用增强,接头连接质量逐渐提高.当T=590℃、t=30 min时,接头抗剪强度达到112.6MPa;当T=590℃、t=50 min时,少量小尺寸SiCp因液态钎料排挤而分散于钎缝,因加工硬化而使接头强度递增7.3％.然而,当T≥595℃、t≥60 min时,SiCp偏聚于钎缝,导致接头组织恶化,且剪切断裂以脆性断裂为主.综合考虑钎焊成本与接头强度使用要求,确定最佳钎焊工艺为590℃、30 min.     

Al-Si合金表面复合材料覆层处理

采用钎焊工艺 ,以Zn Al2 5作钎料 ,N2 作保护气体 ,成功地在Al 9Si基底上结合上Al 9Si 15SiCP 复合材料薄片 ,制成了表面复合材料化的Al 9Si合金试样 ,并对该试样基底与覆层的结合效果作了研究。     

Joining of C/C composite to TC4 using SiC particle-reinforced brazing alloy

Silicon carbide particles were used as reinforcement in the Ag-26.7Cu-4.6Ti (wt.%) brazing alloy for joining C/C composite to TC4 (Ti-6Al-4V, wt.%). The mechanical properties of the brazed joints were measured by shear strength testing. The effects of the volume percentage of SiC particles on the microstructures of the brazed joints were investigated. It is shown that the maximum shear strength of the joints is 29 MPa using 15 vol.% SiC in the brazing alloy which is greater than that with Ag-26.7Cu-4.6Ti brazing alloy alone (22 MPa). Ti is reacted with SiC particles, forming Ti–Si–C compound in the particle-reinforced brazing alloy. Due to this, more SiC particles in the brazing alloy, the thickness of TiC/TiCu reaction layer near C/C composite decreases. Moreover, SiC particles added to the brazing alloy can reduce the CTE of the brazing alloy which results in lower residual stress in the C/C composite-to-metal joint. Both of the above reasons lead to the increasing of the shear strength of the brazed joints. But excessive SiC particles added to the brazing alloy lead to pores which results in poor strength of the brazed joint.     

Evaluation of transient liquid phase bonding between nickel-based superalloys

Induction brazing of Inconel 718 to Inconel X-750 using Ni-7Cr-3Fe-3.2B-4.5Si (wt.-%) foil as brazing filler metal was investigated in this paper. Brazing was conducted at the temperature range 1373–1473 K for 0–300 s in a flow argon environment. Both interfacial microstructures and mechanical properties of brazed joints were investigated to evaluate joint quality. The optical and scanning electron microscopic results indicate that good wetting existed between the brazing alloy and both Inconel 718 and Inconel X-750. Microstructures at joint interfaces of all samples show distinct multilayered structures that were mainly formed by isothermal solidification and following solid-state interdiffusion during joining. The diffusion of boron and silicon from brazing filler metal into base metal at the brazing temperature is the main controlling factor pertaining to the microstructural evolution of the joint interface. The element area distribution of Cr, Fe, Si, Ni and Ti was examined by energy dispersive X-ray analysis. It was found that silicon and chromium remain in the center of brazed region and form brittle eutectic phases; boron distribution is uniform across joint area as it readily diffuses from brazing filler metal into base metal. The influence of heating cycle on the microstructures of base material and holding time on the mechanical properties of brazed joint were also investigated.     

Brazing of SiC and SiCf/SiC composites performed with 84Si-16Ti eutectic alloy: microstructure and strength

The microstructure and strength of brazed joints for monolithic SiC and SiC_f/SiC composites are presented and discussed; the brazing technique is based on the use of the 84Si-16Ti (at%) eutectic alloy. The rather low melting point of the used alloy allows to avoid a degradation of the fibre/matrix-interfaces in the composite materials. All the joints did not show any discontinuities and defects at the interface and revealed a fine eutectic structure. Moreover, in the case of composites, the joint layer appeared well adherent both to the matrix and the fibre interphase, and the brazing alloy infiltration looked sufficiently controlled. High resolving electron microscopic investigations of the microstructure and of the nanochemistry (HREM, EELS, esp. ELNES) revealed atomically sharp interfaces without interdiffusion or phase formation at the interlayer leading to the conclusion that direct chemical bonds are responsible for the adhesion. The joints of SiC_f/SiC composites showed 71 ± 10 MPa shear strength at RT and nearly the same values at 600°C.