液固铸造4343/3003/4343铝合金复合锭的界面组织EI北大核心CSCD

采用液固铸造法制备4343/3003/4343铝合金复合锭,研究了复合锭的界面组织、元素分布和界面结合强度,分析了复合锭的界面结合机理。结果表明：在725-750℃浇注4343铝合金,复合锭的界面冶金结合良好,复合界面清晰平直。复合界面由Al-Si固溶体层和Si,Mn元素扩散层构成,Al-Si固溶体层厚薄均匀,Mn,Si元素的扩散距离分别为10μm和32μm,复合界面的结合强度高于3003铝合金的抗拉强度。液固铸造4343/3003/4343铝合金复合锭的界面复合机理为：4343铝合金熔体首先在3003铝合金锭表面急冷形成Al-Si固溶体,Al-Si固溶体中的Si和3003铝合金中的Mn相互扩散,形成牢固冶金结合的复合锭。     

HT300/7CrMnSiMoV双金属复合铸造汽车模具组织性能的研究

采用扫描电镜、显微硬度计、Instron-3382型力学性能试验机等,对双液复合铸造铸件的界面结合情况、微观组织和力学性能进行研究。结果表明:采用合理的铸造生产工艺,成功制备了满足使用性能要求的HT300/7CrMnSiMoV双金属汽车模具铸件,其复合界面清晰、致密,无明显缩孔、缩松等铸造缺陷;复合界面由钢基体区、过渡区和铁基体区3个区域组成。过渡区呈犬牙状/锯齿形结构,过渡层厚度约为400μm,界面附近Cr和Si元素呈梯度分布,两种合金冶金结合状态良好;复合界面两侧显微硬度呈梯度分布,其抗拉强度达到339 MPa,断裂位置出现在灰铸铁一侧,双金属界面的结合强度高于灰铸铁。     

喷射轧制钢/Al-Pb复合轴瓦带材的组织与性能

采用喷射轧制工艺制备了钢/Al-8.5Pb-4Si-Cu-0.5Sn复合轴瓦带材,分析了所制备材料的组织及性能.结果表明,用喷射轧制工艺制备的轴瓦合金Al-Si基体中分布有均匀细小的Pb相粒子,经过50%变形量的轧制和在320℃后续退火5h的处理,在复合轴瓦带材的界面处发生了合金元素的扩散,形成了良好的冶金结合层,界面强度高,剪切强度达到72MPa.用喷射轧制工艺制备的轴瓦合金具有良好的耐磨性能.     

动态布流平面凝固铸造AA1070/AA7050合金

提出了一种新的用于大尺寸复层铸锭平面凝固铸造的布流系统,并使用软件FLUENT对铸造过程中分流方式对温度场的影响进行了模拟分析,模拟结果表明,使用动态布流时熔体温度的均匀性显著优于定口布流,因而可实现凝固时固/液界面在上升过程中保持平坦。使用动态布流平面凝固铸造方法实现了1070/7050大尺寸双层铝合金的铸造复合,铸造结果表明,复合铸锭中两种铝合金的界面清晰平直,无气孔夹杂等缺陷,实现了冶金结合并存在元素扩散层;7050侧金相组织均匀,厚度方向上无明显宏观偏析。     

爆炸-轧制钛/钢复合板界面结合性能研究

爆炸-轧制法是先通过爆炸复合制坯,再进行轧制生产复合板的一种方法。本文研究了爆炸-轧制法生产的钛/钢复合板的界面金相、结合界面的元素分布情况以及退火温度对界面结合强度的影响等问题,结果表明:爆炸轧制法生产的钛钢复合板的界面近似呈平直状,在界面钢侧有一脱碳层,引起界面附近碳元素的重新分布,对结合性能有重要影响;获得高强度结合的界面特征是:剥离界面钢层上的Ti元素含量在一定范围内,钛层大量粘铁;退火温度对界面的结合强度影响较大,而在相应保温下保温时间影响不明显。     

泡沫铝合金三明治结构结合界面及剪切性能的研究

提出了一种新的泡沫铝合金三明治结构的制备工艺--直接将铝板/混合粉末/铝板通过一次大压下量复合轧制,然后在炉中直接发泡成最终产品的制备工艺.实验成功的制备出铝面板的泡沫铝合金芯的三明治板.讨论了铝面板泡沫铝夹芯板轧制过程中以及发泡过程中界面的结合情况及界面结合机理.结果表明,轧制过程中界面结合属于机械结合,结合机制为薄膜理论;发泡过程中界面结合属于冶金结合,而铝面板与粉末体结合发泡后,界面处则只发生Al原子的互扩散,没有新相生成.剪切实验结果表明,预制坯的界面剪切强度较低,能够直接在界面处剥离开或者将板剥离开一半后将板拉断;而发泡后的泡沫铝夹芯板的界面结合力很强,剪切时断裂发生在芯材中或者铝面板上.     

多层金属复合板的热轧制备方法

提高成材率和复合界面质量是制备多层复合板的难题。本工作提出一种多层复合板的高成材率热轧制备方法,即采用氩弧焊固定各层原料板组成坯料,坯料放入金属套后抽真空,再加热到1000~1200℃进行多道次轧制,成功制备出2.5mm厚的67层复合板。通过金相显微镜及电子显微镜观察和分析了界面组织及元素扩散行为,采用拉伸、剪切实验测定复合板的力学性能,并分析其剪切断口。结果表明:采用两步组坯复合和工艺优化,多层复合板的轧制成材率达90%以上。多层复合板具有良好的结合界面,其抗剪强度达到241MPa。9Cr18和1Cr17镍中间层可以较为有效地阻碍界面附近的碳扩散并改善复合板的组织特征。     

双液金属复合耐磨板厚度对复合层组织和性能的影响

利用双液铸造液膜连接工艺制备大平面的低碳钢/高铬铸铁耐磨板。采用SEM,EDS对复合层进行组织观察及成分分析。结果表明:不同厚度的复合板从低碳钢侧至高铬铸铁侧可以分为低碳钢→珠光体过渡层→复合层→高铬铸铁过渡层,双金属复合层完全实现了冶金结合。通过对复合层区域进行显微硬度分析,从低碳钢至高铬铸铁侧的显微硬度在345~1260HV范围梯度分布。复合层的显微组织主要为γ-Fe+粒状碳化物。高铬铸铁过渡层奥氏体组织呈现垂直复合层方向的树枝状生长,并随着耐磨板厚度的增加,奥氏体生长的方向性逐渐消失。根据低碳钢的温度变化初步建立了相关的温度场数学模型。     

Al/SnPb复合界面显微组织研究

利用机械物理破膜及感应加热的方式在Al表面刷镀一层SnPb合金,制备Al/SnPb复合渡层。借助偏光显微镜(PM),扫描电子显微镜(SEM),高分辨透射电子显微镜(HRTEM),X射线能谱分析(EDS)对结合界面进行表征分析。结果表明,Al/SnPb复合材料结合界面良好,其微观界面呈现出明显的过渡状态的结合特征;结合界面呈现锯齿状咬合在一起,有少量Al-Sn过饱固溶体存在;Sn-Pb合金与Al基体通过过渡层有效连接在一起。     

压力条件下固-液复合法制备铜/锌复合材料的研究

采用压力条件下固-液复合法,在不同的锌液浇注温度下制备了铜/锌复合材料,并对其界面结合质量、组织成分和硬度等进行分析研究。结果表明:在铜板预热温度440℃,锌液浇注温度420℃时,可以获得厚度约为8μm、冶金结合良好的复合界面,此时界面层抗拉强度大于40.86MPa,超过铸态锌基体的抗拉强度;随着锌液浇注温度的升高,界面层厚度增加,抗拉强度降低,界面层生成的金属间化合物(CuZn)增多;界面层硬度显著高于基体硬度。     

Study on casting composite ingot of 4045/3004/4045 aluminum alloys

Two kinds of equipments were designed for casting composite ingots, and three‐layer ingots of 4045/3004/4045 aluminum alloys were prepared by direct‐chill (DC) semi‐continuous casting process, macro‐morphology, microstructure, temperature distribution near the interface, elements distributions and tensile strength of the interface were investigated. The equipment suitable for casting composite ingots was determined, and results show that solid supporting layer with uniform temperature distribution forms near the interface, which ensures the stable casting process. The two different aluminum alloys are well bonded. The criterion for temperature control of solid supporting layer is founded based on the relationship between the interface bonding strength and the temperature of solid supporting layer when contacted by 4045 alloy melt.     

羟基磷灰石／TiO2生物活性复合涂层的研究进展

以钛及合金为基体、HA作涂层的复合材料作为植入物应用很普遍．HA涂层与钛及合金基体的结合强度较低，易出现界面剥落现象；锐钛矿型TiO2陶瓷具有较好的生物相容性，能有效地隔离植入体和生物机体，而且能提高涂层和界面的强度，故制备HA／TiO2生物复合涂层已成为国内外学者的研究热点之一。综述了HA／TiO2生物复合涂层的研究进展。     

Effects of Manufacturing Processes on Microstructure and Properties of Al/A356–B4C Composites

Liquid and semi-solid stir casting processes were applied to fabricate B₄C particles-reinforced aluminum–matrix composites. The effects of manufacturing processes on particle distribution, particle/matrix interface, and mechanical properties of the prepared composites were studied. The results show that particle distribution can be significantly improved by using K₂TiF₆–flux and Ti powders in the liquid stir casting process, whereas in the semi-solid stir casting process it could be improved by decreasing the temperature of the slurry. With additions of Ti, the decomposition of B₄C was prevented, and the interfacial bonding strength was significantly improved due to the fact that a TiB₂ layer formed at the particle/matrix interface. Compared to the matrix, the hardness and tensile strength of the Al–B₄C composite fabricated by the liquid stir casting process were increased by 89.6% and 128.8%, respectively; those of the A356–B₄C composite fabricated by the semi-solid stir casting process had no significant improvement due to the weak particle/matrix interface and the presence of particle porosity clusters.     

SiCf/TC17复合材料界面剪切强度测试与有限元分析

界面强度对钛基复合材料的性能有重要影响。采用纤维顶出实验(push-outtest)对连续SiC纤维增强TC17复合材料的界面剪切强度进行了测试,采用SEM观察了样品的形貌。以纤维/基体完全分离后的摩擦力为出发点,采用有限元方法确定了复合材料成型过程中残余应力的产生温度,并计算了残余应力的分布,比较了顶出实验样品制备前后残余应力的变化情况及样品厚度、体积分数对残余应力分布的影响;采用内聚力模型(CZM)分析了界面的化学结合强度。结果表明:SiCf/TC17复合材料高温成型后的冷却过程中开始产生残余应力的温度为775℃;顶出实验样品制备后界面处生成了残余剪切应力,其大小和分布与样品的体积分数和厚度相关,界面处的残余剪切应力造成了界面剪切强度的测试结果与界面化学结合强度的差异;室温下SiCf/TC17复合材料的界面化学结合强度约为450MPa。     

低频电磁场对n-SiCp/2024复合材料组织与性能的影响

分别采用低频电磁铸造(LFEC)与传统半连续铸造(DC)制备n-SiC_p/2024复合材料铸锭,并对铸锭进行挤压以及T6热处理。通过金相组织观察(OM)、TEM、室温力学性能测试等手段,分别研究了低频电磁铸造与传统半连续铸造工艺对n-SiC_p/2024复合材料的微观组织、力学性能的影响情况。实验结果表明:DC制备的n-SiC_p/2024复合材料铸锭表面局部存在偏析瘤,大多数n-SiC_p团聚在晶界处,只有少数聚集在晶粒内部;LFEC制备的n-SiC_p/2024复合材料铸锭组织晶界清晰,n-SiC_p团聚现象基本消失,组织均匀,晶粒细化效果明显。LFEC制备工艺可以有效细化n-SiC_p/2024复合材料铸锭的晶粒尺寸,其电磁搅拌作用对消除n-SiC_p颗粒的团聚现象有显著作用;与DC工艺相比,LFEC可同时提高复合材料的强度与延伸率。     

K2O·8TiO2W/ZL109复合材料的制备、性能以及界面结构

本文采用挤压铸造方法制备出钛酸钾晶须增强ZL109复合材料(K₂O·8TiO_2w/ZL109 composite),该复合材料的室温和300℃下的抗拉强度与基体金属相当,而在200℃下的抗拉强度却大大高于基体金属。作者用高分辨率透射电镜对该复合材料进行了研究。发现在晶须与铝之间存在着TiO过渡层。     

热循环对碳(石墨)/铝复合材料拉伸强度的影响

研究了四种碳(石墨)/铝复合材料经R.T～450℃温度区间热循环之后拉伸强度的变化。结合扫描电镜的断口分析,对界面结合强度与拉伸强度的关系进行了定性的讨论。      

Metal Pipe Joining with Aluminum Alloy by Ultrasonic Insert Casting

Insert casting of aluminum is widely used in industry. In order to realize better metallurgical bonding between metallic pipe and aluminum alloy castings, a new insert casting method with aided by high-power ultrasound has been developed. The bonding strength between the metal pipe and the cast aluminum alloy was evaluated by shear testing, EPMA analysis at the bonding interface was performed. The experimental results indicate that the application of ultrasonic vibration was effective during insert casting, particularly immediately after the primary a phase began to emerge in the cast aluminum melt. In the case of 6061 Al pipe/AC4C joint, the shear strength was approximately 60 times higher than without ultrasound vibration. This bonding reflects the break up of the oxide film on the aluminum pipe surface by the ultrasound cavitation effect. For the steel pipe/AC4C joint, the bonding shear strength had a several-fold enhancement. Ultrasound may promote a chemical reaction between steel and cast aluminum alloys, leading to excellent bonding.     

Evaluation of the tensile and fatigue behaviour of ingot metallurgy beryllium/aluminium alloys

The tensile and fatigue behaviour of ingot metallurgy beryllium/aluminium alloys produced by Nuclear Metals, Inc., is determined as a function of temperature. The wrought alloy and the casting alloy are both shown to have a very high stiffness to density ratio compared with common structural materials. The wrought alloy was found to have superior fatigue strength, tensile strength and ductility relative to the casting alloy; it also maintained a greater fraction of its tensile strength as a function of temperature. The stiffness of the materials can be readily explained using standard composite theory, where the material is treated as a discontinuous beryllium-reinforced aluminium matrix composite. The strength of the casting alloy is controlled to a large extent by the strength of its aluminium alloy matrix. In contrast, strengthening increments from both dislocation-based mechanisms and load transfer appear to be operative for the wrought material. Fractographic analysis of tensile specimens showed that preferential failure of the aluminium regions or the beryllium/aluminium interfacial regions occurs under certain circumstances. Fracture analysis of fatigue samples revealed no obvious fracture initiation sites and no evidence of limited/controlled crack growth regions. This revised version was published online in November 2006 with corrections to the Cover Date.