铝基复合材料超声波辅助钎焊质量评价

根据铝基复合材料钎焊接头的结构特点,分析了界面的声学信号特征,并采用先进的超声成像法对接头质量进行了检测,同时获得了界面的A扫描信号、B扫描和C扫描图像.研究结果表明,结合A扫描信号、B扫描和C扫描图像的特征,能够判断缺陷类型及其位置,并通过断面金相分析进行了验证.超声成像技术能反映出铝基复合材料钎焊界面的接合状态,可检测出气孔、氧化膜夹杂和未钎透缺陷,为铝基复合材料钎焊的研究提供了有效的检测手段.     

铝基复合材料无损检测研究进展

介绍了铝基复合材料的基本性能、应用情况以及缺陷类型,分析了缺陷产生的原因以及缺陷对铝基复合材料性能的影响,对各种无损检测技术在该领域的适用特点进行了比较,综述了液体渗透法、超声波检测法、射线检测法在铝基复合材料无损检测中的实际应用。     

原位生成铝基复合材料的激光焊接

采用大功率激光器研究新型铝基复合材料TiB2/ZL101的焊接性能,TiB2粒子的存在增加了焊缝熔池粘度降低了熔池流动性,影响了焊缝成形,增加了气孔敏感性.焊缝中气孔主要来源于氢和复合材料中的残留盐.激光焊接过程中较大的冷却速度使得焊缝晶粒非常细小,TiB2粒子在焊缝中分布更均匀,没有出现粒子偏析,主要是因为TiB2粒子是属于纳米级,在凝固过程中被凝固界面前沿所捕获而没有被推移.TiB2粒子没有与铝基体发生界面反应生成脆性相Al3Ti及AlB2,TiB2粒子与Al基体界面结合较好.结果表明,激光焊接后没有破坏TiB2粒子的增强效果.     

Compressive strength of continuous fiber reinforced aluminum matrix composites

Aluminum matrix composites can exhibit exceptionally high compressive strength (ε 4 GPa). The main failure mechanism has been identified to be plastic kinking, although an upper bound seems to be attained when the fibers reach their compressive strength. The experimental results are consistent with a plastic kinking model in strain hardening composites. The important parameters controlling the compressive strength are the composite shear modulus, the shear yield strength, the strain hardening rate and the maximum initial fiber misorientation. Interfaces can also play an important role; composites reinforced with weakly bonded fibers have a reduced compressive strength due to their low shear strength in the fiber direction. The results can be used to design composite systems with high compressive strengths; in practice this is done by selecting matrices with high yield strengths and fast hardening rates.     

汽车铝基复合材料的制备与性能

铝基复合材料具有优异的性能.介绍了铝基复合材料的发展过程、种类及其性能.综述了颗粒、晶须增强材料的制备方法.列举了常用颗粒增强体及晶须增强体的部分特性,指出了铝基复合材料应用潜力及妨碍铝基复合材料广泛应用的主要障碍.     

Material selection and grade optimization applied to aluminum matrix composites

A general model for the optimal use of materials based on structural optimization is derived. The competitiveness of materials is assessed with merit parameters. The competition between materials (material selection optimization) and the role of the composition and microstructure for a given material (grade optimization) are analyzed. The model is applied to aluminum matrix composites. The influence of matrix material, amount of reinforcement, and value of weight savings is studied. Mechanical properties are analyzed with the aid of published experimental data and available models. The Tsai-Halpin model is used to represent the variation of the elastic modulus with the amount of reinforcement. For yield strength the modified shear lag model is applied. It can satisfactorily describe experimental data and the variation with reinforcement for high-strength matrix alloys. For aluminum alloys of medium and lower strength, the observed increase is larger than the predicted one. This can be explained with the help of more recently developed micromechanical models that take into account the changes in microstructure in the matrix. For structural parts, large values of weight savings are usually necessary to make the particulate-reinforced composites competitive with carbon steel or their parent aluminum alloys. In other applications, combinations of properties are important to make the composites competitive.     

铝基复合材料凝固与成形一体化技术

针对铝基复合材料塑性成形困难、增强相与基体金属界面相容性差的问题,提出铝基复合材料凝固与成形一体化技术,实现了铝基复合材料管材、线材和型材的连续近终形成形,并改善粒子相与铝界面相容性和强化作用,达到短流程,低能耗成形的目的.研究了铝基复合材料连续凝固与成形过程的组织演化规律和制品性能,优化了凝固成形条件.     

Tribological stability of particle reinforced aluminum matrix composites in braking

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硼酸铝晶须增强铝基复合材料的显微组织、力学性能和磨损性能（英文）

通过传统的粉末冶金技术制备不同含量硼酸铝晶须(ABOw)(5%, 10%, 15%,质量分数)增强的商业纯铝基复合材料,并对其显微组织特征和力学性能进行研究。采用粉末冶金方法有效混合铝粉和ABOw,将混合粉冷压后在600℃下烧结。通过光学显微镜(OM)、扫描电子显微镜(SEM)、能谱分析(EDS)、透射电子显微镜(TEM)和X射线衍射(XRD)对烧结后的复合材料进行显微组织表征,测定复合材料的孔隙率随ABOw含量的变化,研究ABOw含量变化对复合材料的力学性能,包括硬度、抗弯强度和抗压强度的影响,及复合材料在恒定载荷下、不同滑动距离下的干滑动磨损行为。结果表明,当ABOw含量为10%(质量分数)时,复合材料具有最大的抗弯强度和抗压强度,分别为172 MPa和324 MPa,并且硬度得到改善,约为HV 40.2。但是,随着ABOw含量的进一步增加,性能降低。含10%ABOw复合材料的耐磨性能也得到显著提高。Al-10%ABOw复合材料优异的综合性能归因于其具有良好的界面结合性能、低的孔隙率和好的组织均匀性。     

颗粒增强铝基复合材料激光焊接研究现状及展望

阐述了激光焊焊接铝基复合材料的国内外研究现状,主要对激光焊焊接铝基复合材料时所存在的焊缝成形、气孔、界面反应及粒子分布等问题做了详细的阐述,提出了相应的解决方法,并对激光焊焊接铝基复合材料的前景做出了展望.     

Interface and thermal expansion of carbon fiber reinforced aluminum matrix composites

Two kinds of unidirectional PAN M40 carbon fiber(55%,volume fraction) reinforced 6061Al and 5A06Al composites were fabricated by the squeeze-casting technology and their interface structure and thermal expansion properties were investigated.Results showed that the combination between aluminum alloy and fibers was well in two composites and interface reaction in M40/5A06Al composite was weaker than that in M40/6061Al composite.Coefficients of thermal expansion(CTE) of M40/Al composites varied approximately from(1.45-2.68)×10-6 K-1 to(0.35-1.44)×10-6 K-1 between 20 °C and 450 °C,and decreased slowly with the increase of temperature.In addition,the CTE of M40/6061Al composite was lower than that of M40/5A06Al composite.It was observed that fibers were protruded significantly from the matrix after thermal expansion,which demonstrated the existence of interface sliding between fiber and matrix during the thermal expansion.It was believed that weak interfacial reaction resulted in a higher CTE.It was found that the experimental CTEs were closer to the predicted values by Schapery model.     

SiC增强铝基复合材料焊接特性及其储能焊

分析了SiC增强铝基复合材料的焊接特性。讨论了SiC增强铝基复合材料熔化焊、钎焊和固相焊的研究现状。结合试验,重点探讨了SiC增强铝基复合材料储能焊,分析了储能焊焊接接头的金相组织,其焊接接头由熔核区、熔合区及热影响区组成。由于大的冷却速率使得熔核组织显著细化,具有快速凝固组织特征,表明储能焊可实现铝基复合材料的焊接,且具有独特的优点。     

颗粒增强铝基梯度复合材料的摩擦磨损性能

摘要采用新型喷射沉积技术制备SiC体积分数呈连续分布(0～30%)的Al-Si基梯度复合材料,利用MG-2000型销-盘磨擦磨损试验机,研究不同滑动转速和载荷对该梯度复合材料摩擦磨损性能的影响.采用SEM和MHV-2000型维氏硬度计研究该梯度复合材料的显微组织、硬度及其耐磨性的梯度分布规律.结果表明随着滑动转速和载荷的增大,梯度材料的摩擦因数逐渐降低;材料的磨损率随载荷的增加而增大,随滑动转速的提高先增大后减小,在转速500 r/min时达到最大;对比研究沉积态与热压态材料的摩擦磨损行为,喷射沉积态由于孔隙等缺陷的存在,其磨损形式主要是磨粒磨损和剥层磨损;热压后,梯度材料的磨损形式以磨粒磨损和粘着磨损为主;随基体中SiC含量的逐渐增加,锭坯各部分硬度和耐磨性也随之提高.     

SiC颗粒增强铝基复合材料的连接现状

SiC颗粒增强铝基复合材料因其具有成本低、耐磨性好、高比强度和比刚度、高谐振频率等优良的性能受到关注,但由于难于机械加工,特别是焊接性较差制约其在工程中的应用推广. 文中通过对国内外SiC颗粒增强铝基复合材料的连接现状(焊接方法主要集中于熔化焊、扩散焊、搅拌摩擦焊和钎焊等)进行综述和评价. 结果表明,SiC颗粒和Al基体的较大物理化学性能差异是影响该种复合材料焊接性的主要因素;当SiC颗粒体积分数低于35%时,目前已取得令人基本满意的焊接效果,已具有小批量生产的趋势;但当SiC颗粒体积分数大于35%时,特别是针对高体积分数(55% ~ 75%)的复合材料而言,传统的熔化焊方法很难获得高质量的接头,因此选择合适的连接方法和特殊的焊料成分则成为该种材料的重要创新方向.     

Microstructure characteristics of SiC particle-reinforced aluminum matrix composites by plasma spraying

Aluminum with 55 and 75 vol.% SiC powders were ball milled as plasma spray feedstock. The feedstock was deposited onto a graphite substrate to form a freestanding composite by air plasma spraying. The microstructure characteristics of the sprayed composite were investigated by x-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The SiC volume fraction and porosity in the sprayed composites depend on plasma spray conditions. The silicon phase was formed in the sprayed composites in some plasma spray conditions, and its amount was related to the input of electrical power into the plasma spray. The mechanism of silicon formation was studied. In the sprayed composites, no reaction products could be observed in the Al/SiC interface. Impurity materials from ball media, stainless steel, and ZrO₂ reacted with aluminum and silicon to form complex compounds during plasma spray deposition.     

激光熔铸多壁纳米碳管增强铝基复合材料

利用激光熔铸技术制备多壁纳米碳管增强铝基复合材料,并使用SEM、XRD对其熔铸成形性以及纳米碳管与基体金属界面结合行为进行观察和分析.结果表明,在单位面积激光能量为800×105J/m2时,纳米碳管增强铝基复合材料能够熔合而不破坏纳米碳管结构;在该复合材料中适量添加表面张力较低的金属Mg,可降低基体铝的表面张力,进而降低铝-纳米碳管的液固界面能,改善铝合金和纳米碳管的润湿性;当纳米碳管含量为5%(质量分数)时,并添加3%(质量分数)合金化元素Mg,激光熔铸的复合材料熔合性较好,铸块致密,在复合铸块的断口上能观察到增强体纳米碳管.     

Some observations on hardness measurements of particulate-reinforced 6061 aluminum metal matrix composites

Hardness measurements on a series of particulate- reinforced metal matrix composites in a solution treated and T- 6 condition were carried out using a Vickers microhardness tester at 25-, 50-, 100-, 200-, 300-, and 500-g indenter loads and a Vickers macrohardness tester at an indenter load of 5 kg. It appears that the presence of the particles makes a contribution to the hardness measurement, the degree of which depends on the size and distribution of the particles, and also the indentation load. Although some trends are observed, there is no predictable effect of the material and test parameter on the hardness values.