高强铜/钢双金属复合导板的界面结合机制

采用液态铜与钢复合、液态钢与铜复合两种方案制取了高强铜/钢双金属复合导板。对高强铜/钢双金属复合导板的界面处显微组织、元素分布进行了分析。结果表明,两种复合方式均可使高强铜/钢实现良好的冶金结合;在高强铜/钢双金属的复合过程中,原子优先沿金属表面扩散和晶间渗透,晶界是扩散的主要通道;高强铜/钢双金属界面结合主要通过表面润湿铺展和原子扩散导致富Fe和富Cu区形成Fe-Cu合金相等作用来共同实现。     

铜/钢爆炸复合板浸铝铸件的界面组织

采用扫描电镜技术观察和分析了爆炸复合铜／钢板浸铝铸件的铝／钢界面组织，用面扫描探明了界面组织中主要成份的分布，结合粉末样品的X射线谱确定了界面组织的相组成，用拉剪方法测得了界面的结合强度。结果表明：爆覆在钢板上的铜全部溶入铝液中，界面上出现了Fe2Al5与FeAl3两层连续的中间化合物；同时界面附近还出现了FeAl3颗粒相，这种颗粒相的形成可能和浸铝用钢板的爆炸焊接组织有关。界面的结合强度为80．5MPa。     

几种金属基板上冷喷涂铜涂层的试验与模拟

采用自主研制的冷喷涂设备在三种典型基板上进行喷涂试验,相同的工艺参数下,在铜和铝基板上得到良好的铜涂层,而在钢基板上则没有沉积.实验结果表明:涂层与基板界面、涂层内部颗粒界面结合良好,铜涂层组织致密,显微硬度高达150HV0.1;从涂层表面形貌扫描电镜(SEM)照片中可以观察到射流状的金属,说明颗粒发生了巨大变形,经计算知颗粒在碰撞中压缩率达69%;粉末和涂层的X射线衍射(XRD)结果表明铜粉末在冷喷涂过程中没有发生氧化.同时,数值模拟了铜颗粒与三种基板的碰撞过程,讨论了形成有效结合的判断准则,根据该准则,计算出铜颗粒在铜、铝、钢基板上的临界沉积速度分别为600m/s,500m/s,800m/s,从而解释了铜颗粒在三种基板上不同的沉积行为.     

黄铜/钢扩散复合双金属界面组织与性能

用扫描电镜、能谱分析和压剪试验等方法,研究了扩散退火温度与时间对黄铜/钢扩散复合双金属界面附近组织、成分和界面结合强度的影响.结果表明,通过扩散复合可使黄铜/钢界面实现良好的冶金结合;在一定温度和时间范围内,随扩散温度和时间的增加界面结合面积增大,结合强度增加,可达220MPa;界面附近发生了原子的互扩散,界面上无有害相生成.     

25Cr5MoA／Q235钢固-固复合轴界面特性的试验研究

采用热装法制成了25Cr5MoA钢／Q235固-固复合轴坯料,研究了复合轴挤压成形以及热处理后的界面组织、Cr元素扩散、显微硬度以及结合强度。结果表明：由于采用热装,在结合界面上出现了接近于连续分布的氧化物层,当挤压比为5．6时,挤压变形无法消除氧化皮的影响。结合界面的氧化皮对元素扩散起到阻碍作用,使Cr元素在界面附近Cr元素分布出现跳跃;与挤压态相比,随着保温时间的延长,25Cr5MoA钢与Q235钢结合界面的氧化物层有所改善。当保温时间大于60min时,界面附近硬度峰值消失,显微硬度连续变化区间扩大;复合轴结构上所具有的特点,使其即使结合强度较低,也不易产生剥离,经过后续热处理,通过元素的扩散过程,提高复合轴的结合强度。     

扩散退火和热轧温度对钛铜界面结合强度的影响

对热挤压的钛铜复合棒进行扩散处理,研究扩散退火温度及保温时间对界面结合强度的影响,并通过测试Ti和Cu在高温下的拉伸性能来选择较为合适的热轧温度。结果表明:扩散退火可有效促进界面处金属原子的扩散和增强结合强度,当扩散退火在780～800 ℃/30 min时复合界面的结合强度最高;钛铜复合棒热轧温度应选择780 ℃较为合适,此时Ti、Cu的强度和塑性指标相近,利于热轧时的均匀变形;钛铜复合棒的热轧结合机理可用N.Bay理论、热作用机制及位错学说进行解释。     

CuO添加剂对Ag／SnO2润湿性与界面特性的影响

采用座滴法研究了CuO对Ag/SnO2间润湿角的影响,利用扫描电镜(SEM)和电子探针显微分析(EPMA)测试了试样界面微观形貌及过渡区成分变化.结果表明,随着CuO含量的增加,SnO2与Ag的润湿性提高,7%CuO的加入,使Ag/SnO2的润湿角从90°减小到29°.加入CuO后,液态银渗入氧化物颗粒间隙,同时发生氧化物向银区的扩散,形成牢固的润湿界面.     

搅拌摩擦加工法制备铜/钢复合板工艺探索

探索了用搅拌摩擦加工法制备铜/钢复合板,并对复合板界面区域进行了微观形貌分析和硬度测试.结果表明,随搅拌针插入量的增大,复合板界面区域铜与钢的混合程度增大,搅拌针的磨损程度也增大,搅拌针最佳插入量为0.5mm;在铜/钢复合板的界面上,铜、钢两种成分相互扩散,可得到铜钢固溶体,其硬度最大可达288HV,约为钢母材的1.9倍.     

铜/钢纳米多层复合板异步轧制制备

研究了H62黄铜/Q235钢异步轧制复合试验,即表面处理→轧制复合→轧后热处理.结果表明,异步轧制使铜/钢界面出现焊合现象,铜、铁原子发生互扩散,扩散范围10μm;600℃退火处理使扩散层厚度增大到16 μm,改善了复合效果,制备了0.65 mm厚的铜/钢复合板.     

低Ni/Cu比钢中铜的富集行为

采用热重分析仪和扫描电镜研究了不同加热温度和升温速率下Ni/Cu比为0.39的低Ni/Cu比含铜钢铜富集行为。研究结果表明:在1050～1300℃加热温度范围内,富集相以富Cu-Ni相和富Ni相为主,且以颗粒形式弥散分布于氧化皮内部或氧化皮与钢基体界面;除1250℃外,随加热温度升高,富集相中Ni/Cu比值逐渐增加,在1200℃和1300℃时,富集相仅为富Ni相。加热温度为1250℃时,升温速率不同,富集相的Ni/Cu比值和氧化皮与钢基体界面形态不同:采用5℃/min低速升温和15℃/min高速升温均有利于增加Ni/Cu比值,而采用10℃/min中速升温导致Ni/Cu比值偏低;增加升温速率,缩短加热时间,使氧化皮与钢基体界面更加平滑,有利于除鳞以改善钢材表面质量。对生产高表面质量低Ni/Cu比含铜钢而言,可采取低温加热或高温加热,将加热温度分别控制在1180～1220℃或者1280～1320℃;也可采用1220～1280℃中温加热,将弱氧化性气氛下分阶段步进梁加热炉的第三阶段升温速率控制在15℃/min左右。     

Cu／Al真空扩散焊接显微组织分析

采用真空扩散焊工艺方法,对Cu与Al扩散焊接头的组织性能进行了试验,利用扫描电镜（SEM）、电子探针9EPMA）、显微硬度等测试焊接过渡区及基体组织和性能进行了分析。试验结果表明：采用真空扩散焊工艺,在加热温度530－540℃,保温时间60min,压力11．5MPa时,在Cu/Al界面处形成明显的扩散过渡区,扩散区域宽约40μm。在铜侧过渡区中产生金属间化合物,会出现显微硬度高峰区,控制Al的扩散浓度可避免或减少界面处金属间化合物的产生。     

Al-Si-Cu合金粉末扩散钎焊Al/Cu接头组织及性能

采用Al-Si-Cu合金粉末扩散钎焊铝铜异种金属,采用SEM,EDS和XRD分析接头微观组织结构,结合三元相图分析了接头形成机理,最后检测了接头力学性能.结果表明,在连接温度530℃,保温时间60 min,压力为1MPa时可形成均匀致密的接头,接头中存在大量条状和鱼骨状的Al-Si-Cu共晶组织,中间层与两母材结合界面处的组织结构不同,在靠近铜侧界面存在三种层状金属间化合物,其成分依次为Cu₃Al₂,CuAl和CuAl₂,在靠近铝侧界面存在一个扩散区,没有形成层状金属间化合物.接头的抗剪强度随保温时间的变化而变化,在保温60 min时达到35 MPa.     

The effect of continuous cooling heat treatment on interface properties of SK3/copper compound casting

The bonding of an SK3 steel insert to copper during cast welding and heat treatment was studied. The interface shear strength was made with a push-out test. After cast welding, a cast welding layer formed between SK3 steel and copper. After a continuous cooling heat treatment, there was a cast welding layer near the SK3 steel matrix, an irregular layer near the copper matrix, and a middle layer between them. X-ray diffraction analysis was used to determine that the interface layer consisted of carbon and CuFeO₂. Through electron probe x-ray microanalysis (EPMA), it was shown that mainly iron atoms and carbons diffused into the copper matrix. The interface shear strengths of the compound casting while with water quenched, oil quenched, air cooled, and furnace cooled, were 23.42, 18.74, 12.29, 13.43, and 8.33 MPa, all of heat treatment fractures in the cast welding layer near the SK3 steel matrix.     

Al2O3弥散铜/纯铜扩散焊工艺

采用真空扩散连接工艺,对Al2O3弥散强化铜/纯铜的连接进行了试验研究.用扫描电镜分析了Al2O3弥散强化铜/纯铜扩散界面组织结构,研究了工艺参数对界面结合状态和组织结构的影响.通过正交试验得出各因素对接头抗拉强度的影响大小依次为:扩散温度＞压力＞保温时间.正交试验结果表明:焊接温度为550℃,保温时间为3h,压力为25 MPa时,可获得组织均匀致密、界面连续的Al2弥散铜/纯铜扩散焊接头,且接头抗拉强度高达116.9 MPa.     

Corrosion behavior of copper,tin, and bronze CuSn14 in acid rain solution

The corrosion behavior of copper, tin, and bronze CuSn14 is studied in simulated acid rain (pH 4.5) by electrochemical techniques, cyclic voltammetry and electrochemical impedance spectroscopy. The potentiodynamic formation of anodic oxide film on copper and tin is described in terms of high-field model. Cyclic voltammetry shows that dissolution of bronze is higher than of pure copper metal in acid rain. Electrochemical impedance spectroscopy data reveal that oxide films formed on copper and tin have a higher resistance and suppressed diffusion process through the surface layer than the oxide film formed on bronze CuSn14 at the same conditions.     

Unusual anodic peak on negative potential scan for copper in alkaline media

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Diffusion bonding of titanium alloy to tin-bronze

The vacuum diffusion bonding of titanium alloy to tin-bronze has been studied and the feasibility and appropriate processing parameters have been investigated. The maximum tensile strength of the joints is bonded joint has been observed by SEM, X-ray and EPMA, and the main factors affecting diffusion bonding have been analyzed. The intermetallic compounds Ti2Cu and TiCu were formed near the interface. The width and quantity of the intermetallic compound increases with the increase of the bonding time. The formation of the intermetallic compounds results in embrittlement of the joint and the poor joint properties.     

Influence of diffusion bonding conditions on bonding strength of damping copper alloy to stainless steel

The experimental investigation of different tran sition metals was carried out in the diffusion bonding joints of Cu alloys (CuAlBe) to stainless stee l (1Cr18Ni9Ti). The microstructure of the joint was analyzed with microscopic examination, SEM, EPMA and X-ray diffraction. Following conclusions have been draw n: (1) The joint strength with the Ni interlayer was higher than that with Cu in terlayer when the welding parameters were same;(2)When Ni interlayer was thinner ,Al could interact with Ni and Fe,and the intermetallic compounds,such as Fe3A letc,were formed in the interface,which decreased the strength of the joints;(3 ) When the bonding temperature was higher,because of the diffusion of Cu in Ni being faster than Ni in Cu,a Kirkendall effect was produced,which also decreased the strength of the joints.     

Oxide removal and desorption of oxygen from partly oxidized thin films of copper at low pressures

Partly oxidized copper films were annealed in a controlled vacuum of 10^–7 Pa at a temperature of 450° C. The changes discussed below were observed in situ with a specially designed high-resolution transmission electron microscope. The thin, (100)-oriented, single-crystal films of copper had been oxidized immediately prior to the annealing studies at the same temperature and at an oxygen partial pressure of 7×10 ^–1 Pa, until the desired fraction of the copper film was converted to oxide. It was observed that the oxide disappeared during annealing as long as some copper was left unoxidized. The disappearance of the oxide is explained as being due to dissociation of the oxide at the oxide-metal interface followed by diffusion of oxygen into the metal and desorption of oxygen from the surface of the unoxidized copper. The rate of disappearance of the oxide was found to be proportional to the surface area of unoxidized copper, i.e., the desorption was found to be the rate — limiting step. In the case of heavily oxidized films (>50%), holes were observed to develop in the oxide near the oxide-metal interface after an annealing period of 2–3 hr. Upon resumption of the oxidation, these holes first disappeared, and the normal oxidation behavior was then resumed. The formation of holes may be explained by vacancy clustering. When completely oxidized films were annealed, recrystallization of the oxide was observed.This work was performed at the Ames Research Center and funded by NASA Grants Nos. NCA2-OP390-403 and NSG-2025.     

The oxidation of copper studied by electron scattering techniques

The oxidation of thin single-crystal (100) and (111) films of copper at pressures of around 10^–5 Torr and temperatures of 400 to 700°C has been observed by medium-energy electron diffraction, scanning electron microscopy, scanning and conventional microscopy using diffracted electron beams in the reflection mode, transmission electron microscopy, and transmission electron diffraction. Epitaxed nuclei of oxide are observed to grow into very thin single-crystal plates, using oxygen previously trapped in the copper film. There is considerable diffusion of the copper film. There is considerable diffusion of the copper away from the oxide. Between the oxide crystallites the copper surfaces appear to be unoxidized. A mottled contrast of the diffracted beam images of the copper surface is shown to result from many-beam dynamical diffraction effects.