The effect of cooling rate during multiple reflow soldering on intermetallic layer of Sn‐4.0 Ag‐0.5Cu/ENImAg

The effect of intermetallic compound layer between Sn‐4.0 Ag‐0.5Cu solder bump and electroless nickel/immersion silver (ENImAg) surface finish under different cooling rate during multiple reflow condition was investigated. The results show that the interfacial (Cu, Ni)₆Sn₅ intermetallic compound were formed at the early stage after the first reflow process. After multiple reflow processes, both (Cu, Ni)₆Sn₅ and (Ni, Cu)₃Sn₄ appeared as needle‐shaped at interface due to the amount of copper concentration into a solder balls. The spalling intermetallic compound of (Cu, Ni)₆Sn₅ was spotted in the solder which was caused by the formation of needle‐shaped from the gaps of (Cu, Ni)₆Sn_5. The intermetallic compound thickness and grain sizes became thicker and coarser with increasing reflow time, respectively. The results also perceived that the cooling rate condition can influence the growth of intermetallic compound formation. Faster cooling rate produced thinner intermetallic layer as well as smaller grain sizes compared to slow cooling rate. Hence, the cooling rate is a necessary parameter in the solder reflow process because it has an impact on the microstructure of morphology and intermetallic growth.     

Al含量对Zn-xAl-4Sb合金平衡凝固组织的影响

利用SEM、EDS、XRD研究了不同Al含量的Zn-xAl-4Sb(x=0、0.5、1.0、2.0、4.0、6.0)合金在炉冷条件下(冷却速度0.04℃/s)的凝固组织,探讨了Al和Sb以Zn-Al-Sb三元中间合金加入锌液的可能性.结果表明:合金中的Al优先与Sb生成AlSb相;当Al含量小于1.0%时,随着Al含量的增加,合金中AlSb相的量增加,β-Sb3Zn4相逐渐减少;当Al含量为1.0%时,β-Sb3Zn4相消失,合金组织为Zn基体上分布AlSb相;当Al含量大于1.0%时,合金中出现Zn-Al共晶,且共晶的量随Al含量的增加而增多;用Zn-Al-Sb室温下等温截面的富锌角表示了Zn-xAl-4Sb体系的室温相组成.因Al和Sb形成高熔点AlSb相,很难在锌液中溶解,故Al和Sb不宜以Zn-Al-Sb三元中间合金的方式加入.     

水下搅拌摩擦焊对铝/铜接头组织与性能的影响

目的 采用搅拌摩擦焊,对比分析大气环境和水下环境下铝/铜接头的组织与性能,以期获得力学性能更优异的铝/铜焊接接头。方法 利用搅拌摩擦焊,在焊接速度为40 mm/min、旋转速度为1 000 r/min的条件下,分别在大气环境和水下环境下对厚度为9 mm的6061铝合金板和T2纯铜板进行焊接。然后,对铝/铜界面、焊核区进行扫描电镜及能谱分析,并对铝/铜界面及焊核区进行物相分析,确定产物相组成。最后,对铝/铜试样进行拉伸及硬度检测。结果 铝/铜接头均无裂纹、气孔等缺陷。铜颗粒弥散分布在焊核区,铝/铜界面形成金属间化合物层。水下搅拌摩擦焊下界面元素扩散距离明显变短,且金属间化合物厚度更薄。铝/铜接头的金属间化合物为AlCu和Al4Cu9。大气环境焊接下接头的抗拉强度为130.6 MPa,断裂方式为脆性断裂;水下焊接下接头的抗拉强度为199.5 MPa,断裂方式为韧性断裂。水下环境下的接头硬度值更高,其中热影响区的硬度最低值约为65HV。结论 水下搅拌摩擦焊铝/铜接头无裂纹、气孔等缺陷。组织上,水下搅拌摩擦焊的铝/铜接头界面元素扩散距离更短,硬脆的金属间化合物更少;性能上,水下搅拌摩擦焊的铝/铜接头强度更高,抗拉强度达到199.5 MPa,达到母材的74.4%。     

激光熔覆在金属间化合物涂层材料制备中的应用

在分析金属间化合物涂层材料特点的基础上，综述各种激光熔覆合成金属间化合物涂层的研究现状，分析各种金属间化合物涂层的组织及性能，研究表明激光熔覆合成的金属间化合物涂层均具有优异的耐磨、耐腐蚀、抗氧化等性能。     

Control of mechanical and wear properties of a commercial Al-Si eutectic alloy

The properties examined as a function of microstructural modification were ultimate tensile strength, fracture elongation, Vickers hardness and wear resistance. The microstructural modification was achieved by rapid cooling and additions of small amounts of strontium and lithium master alloys into the eutectic melt. In all experiments the commercial ETIAL 140 alloy was cast instead of a high-purity aluminium-silicon eutectic. This allowed determination of the effect of modification treatment, both on silicon and intermetallic phases. It was found that the slowly cooled and unalloyed castings which contained coarse silicon flakes showed highest wear resistance and lowest ultimate tensile strength, fracture elongation and Vickers hardness values. Rapid cooling and also additions of strontium and lithium master alloys reduced the eutectic interphase spacing and refined the silicon phase. This usually corresponded to a significant increase in all properties except the wear resistance. It was noted, however, that the size of the intermetallic phase particles increased abruptly above 0.04% Sr content which resulted in a sharp reduction in all mechanical properties. Unlike the strontium effect, the lithium addition did not influence the intermetallic size significantly and, therefore, the mechanical properties were not impaired. In addition, the wear resistance also remained relatively unaffected because lithium solid solution hardened the primary aluminium dendrites appeared in the modified alloys.     

金属间化合物的制备及其在化工中的应用

金属间化合物是一种介于金属与陶瓷之间的新型功能与结构材料,近年来在制备方面取得了长足的发展.综述了金属间化合物的若干制备方法,重点是机械合金化法、自蔓延高温合成法、喷射沉积法,简要叙述了上述方法的优点和不足之处.由于本身具有特殊性能,金属间化合物已作为一种新型催化剂被尝试性地应用在化学工程中.结合化学工程学科的特点与需要以及作者自己的研究心得,对金属间化合物的研发进行了探讨.     

Tensile behaviour of polycrystalline Ni3Al intermetallic: influence of environment

Alloys based on the nickel aluminide intermetallic compound are particularly attractive for a spectrum of applications because of their high strength and resistance to oxidation. The inferior ductility of polycrystalline nickel aluminide intermetallic alloy was improved by controlled microalloying with boron. This important development has engendered considerable scientific interest in the use of this novel engineering material for temperature-critical and environment-sensitive applications. In this study, an attempt has been made to rationalize the influence of environment on the tensile behaviour of polycrystalline Ni₃Al alloy containing boron and zirconium. Slow strain tensile tests were performed on cold-deformed and annealed samples in environments of laboratory air, distilled water, and aqueous 3.5% sodium chloride solution. A comparison of the tensile properties and fracture behaviour of the polycrystalline intermetallic alloy in the different environments is made to highlight the role of environment in tensile behaviour.     

Fe3Al基金属间化合物涂层的研究进展

Fe3Al金属间化合物具有良好的高温性能,在钢表面制备Fe3Al基金属间化合物涂层能有效提高基体在高温下的抗氧化、耐腐蚀、耐摩擦和抗冲蚀性能,其抗硫化性能甚至优于不锈钢.相比于同等功能的陶瓷涂层,Fe3Al涂层与基体有更好的相容性.综述了Fe3Al基金属间化合物涂层的研究现状,介绍了涂层性能及影响因素,涂层制备的主要工艺方法和技术特点,主要包括热喷涂、堆焊、激光合成等.     

Interface properties of aluminum/steel friction-welded components

The study of the metallurgy of the interface of metal/metal friction-welded components is essential for understanding the quality of bonding. We have studied, through optical and electron microscopy, and tensile strength measurements, the bonding properties of Al and interstitial free steel and Al and stainless steel friction-welded components. The samples were produced by varying the friction time and rotational speed, friction pressure, upsetting pressure, and upsetting time constant at optimized values reported earlier. The bonding occurs over an intermetallic phase, which, when too thick, influences the bonding properties adversely. The thickness of the intermetallic interlayer depends linearly of on the square root of the friction time, indicating that the growth is caused by diffusion. The effect of oxidation on the bonding is also studied on samples prepared under argon atmosphere and normal atmosphere.     

Interface properties of aluminum/steel friction-welded components

The study of the metallurgy of the interface of metal/metal friction-welded components is essential for understanding the quality of bonding. We have studied, through optical and electron microscopy, and tensile strength measurements, the bonding properties of Al and interstitial free steel and Al and stainless steel friction-welded components. The samples were produced by varying the friction time and rotational speed, friction pressure, upsetting pressure, and upsetting time constant at optimized values reported earlier. The bonding occurs over an intermetallic phase, which, when too thick, influences the bonding properties adversely. The thickness of the intermetallic interlayer depends linearly of on the square root of the friction time, indicating that the growth is caused by diffusion. The effect of oxidation on the bonding is also studied on samples prepared under argon atmosphere and normal atmosphere.     

Artificial neural network processing of stripping analysis responses for identifying and quantifying heavy metals in the presence of intermetallic compound formation

Feed-forward neural networks have been trained to identify and quantify heavy metals in mixtures under conditions where there were significant complications due to intermetallic compound formation. The networks were shown to be capable of (i) correlating voltammetric responses with individual heavy metals in complex mixtures, (ii) determining the relationship between responses and concentrations (including nonlinear relationships due to overlapping peaks and intermetallic compound formation), and (iii) rapidly determining concentrations of individual components from mixtures once trained. Using simulated data, modeled after complex interactions experimentally observed in samples containing Cu and Zn, it has been demonstrated that networks containing two layers of neurons (a nonlinear hidden layer and a linear output layer) can be trained to calculate concentrations under a variety of complicated situations. These include, but are not limited to, cases where the response of the intermetallic compound formed is observed as a shoulder of one of the pure metals and cases where the response of the intermetallic compound formed is not observed in the potential window. In addition, the network described above was trained to simultaneously determine concentrations of four metals (Cu, Pb, Cd, and Zn) in a concentration range where all responses were complicated by intermetallic compound formation (1-500 ppb).     

Ultrasonic evaluation of friction stud welded AA 6063/AISI 1030 steel joints

Friction stud welding is a promising technique in many applications related to oil and gas industries. It is used to attach grating to offshore oil platforms in areas where arc welding is not permitted because of the risk of causing a fire or explosion. Attachment of anodes inside seawater discharge pipelines in a gas processing plant is performed by this process. This solid state joining process permits metal combinations such as welding of aluminum studs to steel which would be problematic with arc welding because of the formation of thick and brittle inter-metallic compounds. In the present work, AA 6063 is joined to AISI 1030 steel using friction stud welding machine. Properties that are of interest to manufacturing applications such as Young’s modulus, longitudinal velocity, bulk modulus and shear modulus are evaluated by means of an ultrasonic flaw detector. At the interface of the joint, there is an increase of 4.4%, 1.8%, 1.15% and 4.42% is observed for the properties Young’s modulus, longitudinal velocity, bulk modulus and shear modulus respectively. This is due to the formation of intermetallic compound and increase in hardness at the interfacial region. Energy Dispersive X-ray analysis confirms the presence of FeAl as the intermetallic compound. Scanning Electron Microscope evaluation shows the presence of an unbound zone at the center of the inner region which is due to the minimum rotational speed and low axial load experienced at that point. In the unbound zone, there is an incomplete bond between dissimilar metals and it is detrimental to joint strength. Optimum value of friction time and usage of pure aluminum interlayer during the friction stud welding process hinders the formation of unbound zone and enhances the quality of AA 6063/AISI 1030 joints. The tensile strength of AA 6063/AISI 1030 joint was found to be 36.64% and 78.15% lower than that of AA 6063 and AISI 1030 respectively. Reasons for lower joint strength are attributed to low frictional pressure, non-optimal rotational speed and friction time, improper mechanical mixing, presence of oxide layer and formation of brittle intermetallic compound at the joint interface.     

层状镁/铝复合板轧制工艺研究进展

镁/铝复合板具有密度小、比强度高和耐腐蚀性好等优点,广泛应用于航空航天、汽车制造等领域.轧制法是目前生产镁/铝复合板最为广泛的一种方法,该法设备简单、操作容易、成本低廉.介绍了普通轧制法、异步轧制法、爆炸+轧制法、累积叠轧法、固-液铸轧法、波-平轧制法6种轧制工艺,以及这些工艺在制备镁/铝复合板时的优缺点.波-平轧制工艺可以提高复合板的平直度,有利于板材后续加工成形.也研究了轧制温度、轧制压下率、轧制速度、轧后退火处理对镁/铝复合板力学性能的影响,镁/铝界面金属间化合物的形成因素,以及化合物层厚度对镁/铝复合板力学性能的影响.     

Mechanical and corrosion properties of P/M-HIP super duplex stainless steel after different industrial heat treatments as used for large components

Abstract

Mechanical tensile and impact toughness tests and critical pitting corrosion temperature (CPT) tests were performed on samples of Duplok 27, a P/M-HIP duplex stainless steel containing copper, after heat treatments simulating industrial heat treatments of large components. It was shown that copper alloying has positive effects on mechanical tensile properties leading to hardening and more uniform deformation. No negative effects of copper alloying on corrosion resistance properties were found. A drastic drop in impact toughness values and CPT of samples cooled at controlled cooling rates is explained by the precipitation of intermetallic secondary phases or their precursors. Lower CPT of a NG-GTAW (narrow gap gas tungsten arc welding) welded joint is explained by the lower level of alloying than that of the base material. The high temperature region of precipitation of intermetallic secondary phases is shifted towards higher temperatures than assumed for Duplok 27 P/M-HIP duplex stainless steel.     

WC含量对Ni3Al-WC复合材料组织的影响

以WC，NiAl,NiB和Ni粉等球磨混合粉末烧结制备Ni3Al-WC复合材料焊条，用氩弧焊堆焊在1Cr25Ni20Si2耐热钢的表面形成Ni3Al-WC复合材料。当WC的含量从5%提高到30%时，在焊接过程中，由于熔池中溶解碳含量的增加，保护能力不断增强，溶池中的Al由部分氧化至完全不氧化，冷却后复合材料的组织也从碳化物包裹的氧化物/金属间化合物转变成碳化物/金属间化合物，获得无裂纹的焊接表面。     

Optical properties of coloured platinum intermetallic compounds

The optical properties of the intermetallic compound PtAl₂ were altered by the addition of 5% –25% copper by mass. It was found that these additions cause the colour of the compound to change from the brass-yellow of PtAl₂ through orange to copper-pink. The colour of the intermetallic compounds has been described using the CIELab and chromaticity colour-measuring systems. The effect of the copper additions on the lattice parameter and band structure is discussed, related to the associated change in colour of the intermetallic compound. The effect of the copper additions on the physical and mechanical properties of the material has been studied.     

A study on NiAl produced by pressure-assisted combustion synthesis

The production of intermetallic compound was carried out in an electrical resistance furnace in open air under 150 MPa uniaxial pressure at 1050 °C for 1 hour using aluminum powder with 15 μm size and Carbonyl-nickel powder with 4-7 μm size having 99% and 99.8% purity, respectively. The formation temperature of intermetallic compound was determined by Differential Scanning Calorimeter analysis, and exothermic reaction of powder mixture was determined to occur at 655 °C. Optical microscope, scanning electron microscopy and X-ray diffraction analysis were used to characterize produced samples. These samples consist of single phase NiAl with very low porosity. Based on the Archimedes' principle, the relative density of the samples was 99.6%. The microhardness of the samples was approximately 367 ± 17 HV_1.0. It was observed that NiAl intermetallic exhibited good oxidation resistance at high temperatures in open atmosphere. The distribution of alloying elements within intermetallic compound was determined by energy-dispersive X-ray spectroscopy.     

Parameters controlling the microstructure of Al–11Si–2.5Cu–Mg alloys

This study investigated the effects of cooling rate during solidification, heat treatment, and the addition of Mn and Sr on the formation of intermetallic phases in Al–11Si–2.5Cu–Mg alloys. Microstructures were monitored using optical microscopy and EPMA techniques. The results reveal that the volume fractions of intermetallic phases are generally much lower in the furnace-cooled samples than in the air-cooled ones due to the dissolution of the β-AlFeSi and Al₂Cu phases during slow cooling at critical dissolution temperatures. Strontium additions increased the volume fraction of the Al₂Cu phase in the as-cast conditions at low and high cooling rates, as well as at varying ranges of Mn levels. Platelets of the β-AlFeSi phase were to be observed in the microstructure of the as-cast air-cooled samples with a DAS of 40 μm at both Mn levels, while none of these particles were to be found in the furnace-cooled samples with a DAS of 120 μm. Sludge particles were observed in almost all of the air-cooled alloys with sludge factors of between 1.4 and 1.9. These particles, however, were not observed in the furnace-cooled alloys with similar sludge factors. Solution heat treatment coarsens the Si particles in the non-modified alloys under both sets of cooling conditions studied. In the Sr-modified alloys, solution treatment has varied effects depending on the cooling rate and the level of Mn present.     

焊接速度对Mg/Cu异种合金搅拌摩擦焊接接头成形的影响

目的研究不同焊接速度条件下镁铜异种合金搅拌摩擦焊接接头的成形规律。方法在保证其他焊接工艺相同的条件下,通过改变焊接速度,比较分析了焊接速度对接头的表面成形、横截面形貌特征、微观结构及力学性能的影响规律。结果随着焊接速度从118 mm/min减小至95 mm/min时,焊缝表面成形变得更光滑,飞边显著减少,内部孔洞缺陷消失,焊缝成形质量显著提高;但继续减小焊接速度至75 mm/min时,焊缝内部却再次出现孔洞缺陷。结论采用工艺参数为950 r/min的旋转速度、95 mm/min的焊接速度焊接时,焊缝成形质量最高;中心混合区主要由层片状铜合金、颗粒状镁合金和金属间化合物Mg2Cu组成;接头抗拉强度最大,达81.5 MPa。     

Steady motion of a crack parallel to a bond plane—further results

The present analysis concerns the steady propagation of a crack of length 2a, parallel to a bond plane between two half-planes having different material properties. The crack speed is less than the transverse wave speed of the half-plane in which it is located, but the material properties of the uncracked material are such that the shear or dilatational wave speeds may be exceeded. A transition speed is seen to exist above which the uncracked medium tends to act as a stiffened material.