Cr20Ni32AlTi合金平衡相的热力学模拟计算与分析

通过热力学计算软件Thermo-Calc与相应的Ni基数据库,进行了耐热耐蚀合金Cr20Ni32A1Ti(％:0.10C、0.83Mn、0.56Si、＜0.005P、0.013S、20.89Cr、32.60Ni、0.26A1、0.39Ti、0.009 0N、0.076Cu)化学成分对主要析出相影响的研究,并分析了合金成分对合金初熔点和终熔点的影响.通过SEM、TEM和X射线能谱法对Cr20Ni32AlTi合金的组织和析出相成分进行了实验研究.结果表明,Cr20Ni32AlTi合金的主要析出相为M23C6和M(CN)碳化物,C含量(0.02％～0.10％)显著影响M23C6碳化物的析出量和开始析出温度;Cr含量(20％～22％)和C含量均影响合金的初熔点和终熔点.     

以Nb为中间层AgCuTi为钎料连接炭/炭复合材料与不锈钢

在连接温度为900℃、保温时间10 min的条件下,以Nb为中间层,采用AgCuTi钎料对炭/炭复合材料与不锈钢进行连接.利用扫描电镜和X射线衍射对接头界面组织进行分析.实验结果表明,以Nb为中间层、AgCuTi为钎料能很好地连接炭/炭复合材料与不锈钢;连接过程中,钎料中的Ti向炭/炭复合材料界面区聚集并形成含TiC的...     

Microstructural Evolution of the Interface Between Pure Titanium and Low Melting Point Zr-Ti-Ni(Cu) Filler Metals

Low melting point Zr-based filler metals with melting point depressants (MPDs) such as Cu and Ni elements are used for titanium brazing. However, the phase transition of the filler metals in the titanium joint needs to be explained, since the main element of Zr in the filler metals differs from that of the parent titanium alloys. In addition, since the MPDs easily form brittle intermetallics, that deteriorate joint properties, the phase evolution they cause needs to be studied. Zr-based filler metals having Cu content from 0 to 12 at. pct and Ni content from 12 to 24 at. pct with a melting temperature range of 1062 K to 1082 K (789 °C to 809 °C) were wetting-tested on a titanium plate to investigate the phase transformation and evolution at the interface between the titanium plate and the filler metals. In the interface, the alloys system with Zr, Zr₂Ni, and (Ti,Zr)₂Ni phases was easily changed to a Ti-based alloy system with Ti, Ti₂Ni, and (Ti,Zr)₂Ni phases, by the local melting of parent titanium. The dissolution depths of the parent metal were increased with increasing Ni content in the filler metals because Ni has a faster diffusion rate than Cu. Instead, slow diffusion of Cu into titanium substrate leads to the accumulation of Cu at the molten zone of the interface, which could form undesirable Ti _x Cu _y intermetallics. This study confirmed that Zr-based filler metals are compatible with the parent titanium metal with the minimum content of MPDs.     

Effects of applied pressure on the brazing of superplastic INCONEL 718 superalloy

A superplastic INCONEL 718 superalloy was brazed with a Ni-P and a Ni-Cr-P amorphous filler metal. The effects of applied pressure on the bonding strength, microhardness, and corrosion resistance were studied. The results showed that the brazements with Ni-Cr-P filler metal have higher bonding strength and better corrosion resistance than those with Ni-P filler metal using a conventional brazing method without applied pressure. When brazing was conducted under applied pressure, the bonding strength increased with applied pressure for the brazements with both filler metals. This was caused by a decrease of intermetallic phase through ejection of the liquid phase enriched with melting temperature depressants in the molten filler metals from the joint clearance. Corrosion tests show that these brazements failed at the brazed joint and at the grain boundaries in the region adjacent to the brazement.     

Development of a new CuNiTiB brazing alloy for joining Si3N4 to Si3N4

Joining Si₃N₄ to Si₃N₄ was carried out initially with a Cu₃₄Ni₂₇Ti₃₉ brazing alloy prepared by double melting under a vacuum condition. However, the strength of the joints was not as high as expected. The causes were studied. Based on the results of the analysis, a CuNiTiB brazing filler metal was designed. The Si₃N₄/Si₃N₄ joints were then brazed with this new brazing alloy in the paste form, and joints with a three-point bend strength of 338.8 MPa at room temperature were obtained. The interfacial reactions of the joint are also discussed. With the rapidly solidified foils of the brazing alloy, the bend strength of the Si₃N₄/Si₃N₄ joints under the same brazing conditions is raised to 402 MPa at room temperature. The Si₃N₄/Si₃N₄ joints brazed with this newly developed brazing alloy exhibit a rather high and steady bend strength (about 406 MPa) at 723 K.     

SOME MECHANICAL PROPERTIES OF SAE 1045 STEEL JOINTS BONDED WITH SINTERED COMPACTS

Abstract

The physical and mechanical properties of plain steel (SAE 1045) butt joints, bonded with a sintered alloy as a filler material, are described. Sintered alloys were made from two types of iron powders–electrolytic and Swedish sponge– with various additions ranging from 7 to 20 wt.-% of an electrolytic copper powder, a prealloyed bronze powder (90% Cu+ 10% Sn), and a mechanically mixed elemental bronze powder.

The results showed that the tensile strength was not reduced as drastically as that of the copper-brazed joints, when the thickness of the bonding material (sintered alloy) was increased. The highest bond strength in tensile and fatigue testing was obtained with the sintered alloys comprising iron powder and 10 wt.-% pre alloyed bronze powder. The results indicate that there is a practical possibility of brazing steel using sintered compact as a filler material under a neutral or a reducing atmosphere.     

钎焊温度和热处理对钨铜连接性能的影响

采用厚20 μm的非晶态Ti-Zr-Ni-Cu钎料,真空钎焊连接用于聚变堆面向等离子体部件的钨和铜铬锆合金,钎焊温度分别为860、880和900℃,对880℃下的钎焊样品进行热等静压(HIP)处理.采用SEM和EDS分析连接接头的形貌和成分,用静载剪切法测量焊接接头强度.测试结果表明在860～880℃下钎焊10 min能够获得较好的连接界面,经880℃钎焊后焊接接头的剪切强度为16.57 MPa,880℃钎焊后HIP处理的试样界面结合强度提高至142.73 MPa,说明真空钎焊后HIP处理可以显著改善接头的结合强度.     

The interaction of reaction-bonded silicon carbide and inconel 600 with a nickel-based brazing alloy

The objective of the present research was to join reaction-bonded silicon carbide (RBSC) to INCONEL 600 (a nickel-based superalloy) for use in advanced heat engine applications using either direct brazing or composite interlayer joining. Direct brazing experiments employed American Welding Society (AWS) BNi-5, a commercial nickel-based brazing alloy, as a filler material; composite interlayers consisted of intimate mixtures of α-SiC and BNi-5 powders. Both methods resulted in the liquid filler metal forming a Ni-Si liquid with the free Si in the RBSC, which, in turn, reacted vigorously with the SiC component of the RBSC to form low melting point constituents in both starting materials and Cr carbides at the metal-ceramic interface. Using solution thermodynamics, it was shown that a Ni-Si liquid of greater than 60 at. pct Ni will decompose a-SiC at the experimental brazing temperature of 1200 ‡C; these calculations are consistent with the experimentally observed composition profiles and reaction morphology within the ceramic. It was concluded that the joining of RBSC to INCONEL 600 using a nickel-based brazing alloy is not feasible due to the inevitability of the filler metal reacting with the ceramic, degrading the high-temperature properties of the base materials.     

稀土元素对低温铝基钎料性能影响的研究

本文研究了稀土元素Ｙ、Ｃｅ对Ａｌ－Ｚｎ－Ｃｕ－Ｓｉ系列低温铝基钎料的熔化温度、钎焊工艺性、电极电位及其接头的机械性能及抗腐蚀性能的影响。结果表明：少量Ｙ、Ｃｅ的加入，对钎料的熔化温度影响不大，能提高钎料的钎焊工艺性；稀土Ｙ、Ｃｅ能细化晶粒，改变组织的分布状态，不改变钎料的电极电位，但却提高了钎焊接头的机械性能和抗腐蚀性。     

Thermochemical Analysis of Phases Formed at the Interface of a Mg alloy-Ni-plated Steel Joint during Laser Brazing

The thermodynamic stability of precipitated phases at the steel-Ni-Mg alloy interface during laser brazing of Ni-plated steel to AZ31B magnesium sheet using AZ92 magnesium alloy filler wire has been evaluated using FactSage thermochemical software. Assuming local chemical equilibrium at the interface, the chemical activity–temperature–composition relationships of intermetallic compounds that might form in the steel-Ni interlayer-AZ92 magnesium alloy system in the temperature range of 873 K to 1373 K (600 °C to 1100 °C) were estimated using the Equilib module of FactSage. The results provided better understanding of the phases that might form at the interface of the dissimilar metal joints during the laser brazing process. The addition of a Ni interlayer between the steel and the Mg brazing alloy was predicted to result in the formation of the AlNi, Mg₂Ni, and Al₃Ni₂ intermetallic compounds at the interface, depending on the local maximum temperature. This was confirmed experimentally by laser brazing of Ni electro-plated steel to AZ31B-H24 magnesium alloy using AZ92 magnesium alloy filler wire. As predicted, the formation of just AlNi and Mg₂Ni from a monotectic and eutectic reaction, respectively, was observed near the interface.     

Ni元素对Al-Si-Cu基真空钎焊料接头性能的影响

研究了添加Ni的Al-Si-Cu基钎料真空钎焊LF21铝合金接头的力学性能、微观组织形貌.结果表明,采用添加Ni元素的真空钎料,可提高钎焊接头的剪切强度,其机制在于Ni元素能够改善LF21铝合金真空钎焊接头焊缝及其基体组织的分布.但随着Ni元素含量的增加,其钎料的熔点也有所提高.     

Effects of Rare Earths on Properties of Ti-Zr-Cu-Ni Base Brazing Filler Alloys

The effects of the addition of rare earths on the properties of Ti-Zr-Cu-Ni base brazing filler alloys and the mechanical microstructure and properties were studied for the brazed-joints in the vacuum brazing of TC4 by comparing synthetical properties of two kinds of filler metals.The results indicate that the filler metals added with rare earths have lower melting point, better wettability and higher mechanical properties in the brazing joints.     

Effect of strontium and SmO on the microstructure and fracture mode of AlSi-Mg_2Si brazing filler metal

An AlSi-Mg_2Si self-fluxing brazing filler metal was obtained by activating Al Si brazing filler metal with the Mg_2Si phase and applying a metamorphism treatment of Mg_2Si and Si crystals with Sr and Sm O. A good wetting performance between the modified AlSi-Mg_2 Si and 3003 Al alloys was achieved in the vacuum brazing without Mg vapour as the activator. The melting point of the brazing filler was measured by STA409 Pc differential scanning calorimetry. A scanning electron microscope was used to analyse the microstructure and the component distribution of the brazing filler. The results indicated that the change in morphology of the Mg_2 Si phase was remarkable after metamorphism. The analyses of the microstructure indicated that the Mg_2 Si and Si phases presented small needle-type and granular morphologies. The follows were found to occur: intergranular penetration of Mg and Si on the base metal, a large amount of granular eutectic structure, and a significant grain boundary effect. The shear fracture of the lap joint presented cleavage fracture; in addition, with the decrease of the Mg_2 Si phases, the fracture morphology transformed from a rock candy shape to a steam shape, and cleavage steps appeared. The rock candy-shaped fracture areas enlarged after metamorphism treatment.     

Mechanical Properties and Metallurgical Characterization of Dissimilar Welded Joints between AISI 316 and AISI 4340

In the present study, the influence of six different process parameters and three interactions on joint tensile strength, toughness, fusion zone microhardness variation are studied during dissimilar tungsten inert gas welding between austenitic stainless steel AISI 316 and alloy steel AISI 4340. Detailed experimental study using fractional factorial experimental design and subsequent statistical analysis show that higher tensile strength, toughness can be achieved using ER 309 filler material and suitably selecting the other process parameters and heating conditions. Addition of small proportion of hydrogen in shielding gas increases the heat transfer efficiency, melting and subsequent penetration. Preheating of AISI 4340 material reduces the chance of solidification cracking and post-heating helps to improve the joint mechanical property. Microstructural observations show that improper selection of process parameters may lead to micro-pores and degrade the joint quality. Successful joining of the dissimilar materials greatly depends on the selection of optimum process parameters, filler material and shielding gas.     

Interfacial morphologies between NiO–YSZ fuel electrode/316 stainless steel as interconnect material and B‐Ni3 brazing alloy in solid oxide fuel cell system: effect of joint loading during brazing

Abstract

Joining of NiO–YSZ composite with 316 stainless steel was carried out using B‐Ni3 brazing filler alloy (Ni–4·5Si–3·2B–0·06C–0·02P, wt‐%; melting point, 982–1038°C) and two samples were fabricated. On the one hand, interfacial (chemical) reactions during brazing at the NiO–YSZ/316 stainless steel interconnect were promoted only by addition of an electroless nickel plate to NiO–YSZ composite as a coating with relevant process variables and procedures optimised during the electroless nickel plating. On the other hand, moderate loading was applied during brazing normal to the joint surface where electroless nickel plate was coated previously to improve interfacial sealing of the NiO–YSZ cermet anode/316 stainless steel interconnect structure for use in a solid oxide fuel cell. A special fixture for static loading was designed for filler metal alloy strips to be preplaced at the joint surface where static loading was applied perpendicular to it for the promotion of liquid alloy layer formation during brazing. Brazing was performed in a cold wall vacuum furnace at 1080°C and post‐brazing examination of interfacial morphologies between NiO–YSZ composite and 316 stainless steel was performed using SEM and EDS analyses. The results indicate that B‐Ni3 brazing filler alloy was fused fully during brazing and continuous interfacial layer formation and joint integrity were significantly affected by applied static loading during brazing. The loading most probably contributed to promotion of the B‐Ni3 liquid phase formation in the joint. However, the thickness of the interface area remained almost the same at 100?μm for loaded and unloaded joints.

On a assemblé le composite NiO–YSZ avec l’acier inoxydable 316 en utilisant l’alliage d’apport de brasage B‐Ni3 (4·5% en poids Si, 3·2% en poids B, 0·06% en poids C, 0·02% en poids P, et le reste, Ni, point de fusion 982–1038°C) et l’on a fabriqué deux échantillons. D’un côté, on a stimulé les réactions interfaciales (chimiques) lors du brasage à l’interconnexion NiO–YSZ/acier inoxydable 316 uniquement par addition d’un revêtement autocatalytique de nickel au composite NiO/YSZ, les variables pertinentes du procédé et les procédures étant optimisées lors du dépôt autocatalytique de nickel. D’un autre côté, lors du brasage, on a appliqué une charge modérée, normale à la surface du joint, où l’on avait auparavant déposé le nickel autocatalytique, pour améliorer le scellement interfacial de la structure de l’interconnexion de l’anode cermet NiO–YSZ/acier inoxydable 316 pour utilisation dans une SOFC (pile à combustible à oxyde solide). On a créé un montage spécifique pour charge statique pour que les rubans d’alliage de métal d’apport soient préplacés à la surface du joint où la charge statique était appliquée perpendiculaire à celui‐ci pour promouvoir la formation d’une couche d’alliage liquide lors du brasage. On a effectué le brasage dans un four à vide à paroi froide à 1080°C et, après le brasage, on a examiné les morphologies interfaciales entre le composite NiO–YSZ et l’acier inoxydable 316 en utilisant les analyses de SEM et d’EDS. Les résultats indiquent que l’alliage d’apport de brasage B‐Ni3 était complètement fusionné lors du brasage et la formation d’une couche interfaciale, continue, ainsi que l’intégrité du joint étaient affectées significativement par la charge statique appliquée lors du brasage. La charge a fort probablement contribué à la promotion de la formation de la phase liquide de B‐Ni3 dans le joint. Cependant, l’épaisseur de la région d’interface demeurait presque la même à 100?μm pour les joints avec ou sans charge.     

几种不同银基钎料对钛合金/不锈钢钎焊焊缝的影响

采用不同成分的钎料在相同温度、相同时间条件下，利用光学显微镜，扫描电子显微镜(SEM)等检测手段，对钛合金／不锈钢钎焊焊缝进行了观测分析，并对钎焊接头中形成的不同相的特征以及金属间化合物对接头结合性能的影响进行了分析探讨。     

工艺参数对高铟高锡银基钎料粉末电磁压制成形的影响

根据离散元相关理论, 利用EDEM软件对高铟高锡银基钎料粉末电磁压制过程进行仿真模拟, 探究工艺参数对Ag–Cu–Sn–In系钎料压制过程中的影响规律, 分析钎料粉末的致密化行为, 并研究Sn元素和In元素对钎料粉末相对密度的影响; 在不同电压和电容条件下, 对Ag–19.5Cu–15In–15Sn钎料粉末压制过程进行了仿真模拟, 分析不同放电参数对压坯相对密度的影响; 最后通过压制设备制备钎料压坯, 对仿真结果进行验证。结果表明, 在相同压制力下, In质量分数越高, 获得的压坯相对密度越大; 在电容相同的情况下, 电压越大压坯的相对密度越大, 但增幅逐渐减缓; 在电压相同的情况下, 电容越大压坯的相对密度越大, 但增幅大致不变。实验验证结果表明, 仿真误差小于8%, 钎料电磁压制离散元仿真模型具有一定的参考价值。     

Thermo-Calc calculations and studies of the heating process of Fe83Si4B13 alloy

The microstructural changes of Fe_(83)Si_4B_(13) amorphous mother alloy during the heating process were investigated by Laser Scanning Confocal Microscopy( LSCM),and the phase transformation was determined by the Thermo-Calc calculations. The differences in the melting points measured by Differential Scanning Calorimetry( DSC)and LSCM,and those obtained by Thermo-Calc calculations were also discussed. It is found that the melting points measured by DSC and LSCM are relatively similar,whereas the onset and end of the melting temperatures calculated by Thermo-Calc software are higher than those measured by DSC and observed by LSCM.