FSP和颗粒增强耦合工艺下铝基复合材料制备的研究进展

搅拌摩擦焊发展起来的搅拌摩擦加工(FSP)技术因具有优异的微观组织、不产生的界面反应等优点在颗粒增强铝基复合材料的制备方面得到广泛研究。首先综述了影响搅拌摩擦加工的工艺参数,包括旋转速度、移动速度、下压量以及搅拌道次。这些参数影响搅拌时的热输入,同时热输入会改变复合材料的塑性流动,从而影响复合材料的结构和力学性能。然后重点讨论了搅拌摩擦加工铝基复合材料的工艺方法,通过开孔或开槽法添加强化颗粒的直接加工工艺存在着颗粒团聚的问题,严重影响材料的力学性能,而搅拌摩擦加工作为二次成形工艺间接加工复合材料可以有效提高复合材料力学性能。最后提出目前搅拌摩擦加工工艺在颗粒增强铝基复合材料的制备与发展方面存在的问题以及发展趋势。     

钢搅拌摩擦焊接及加工研究进展

自搅拌摩擦焊发明至今,国内外开展了大量的有关搅拌摩擦焊(Friction stir welding, FSW)技术的研究与开发工作,并且已在轻合金结构制造领域得到大量实际应用。此外,基于搅拌摩擦焊原理发展而来的另一项技术--搅拌摩擦加工也得到广泛关注,并且在金属材料组织改性及复合材料制备方面显示了独特的优势。然而,由于受到高温搅拌头材料的限制,对钢铁材料搅拌摩擦焊接及加工的研究相比铝合金要少了很多。本研究对钢铁材料搅拌摩擦焊接及加工的研究进展进行简要概述,总结同质钢铁材料搅拌摩擦焊接、异质钢铁材料搅拌摩擦焊接、钢铁材料搅拌摩擦加工以及高温焊接工具材料等几方面的研究成果,指出其中存在的重要科学及技术问题,并对钢铁材料搅拌摩擦焊接以及搅拌摩擦加工的发展趋势及值得关注的问题进行展望。     

搅拌摩擦加工道次对PI/7075铝基复合材料显微组织和耐磨性能的影响

在7075铝合金表面预置聚酰亚胺(PI)颗粒,利用搅拌摩擦加工(FSP)技术在不同加工道次下制备PI/7075铝基复合材料,研究了加工道次对复合材料显微组织和耐磨性能的影响。结果表明:增加加工道次可以减少复合材料内部缺陷,提高晶粒细化程度以及PI颗粒在铝合金基体中的分散性;复合材料的耐磨性能优于7075铝合金的,且随着加工道次的增加,耐磨性能提高;不同道次搅拌摩擦加工复合材料的磨损表面均存在少量犁沟和较浅的磨痕,其磨损机制均为黏着磨损和磨粒磨损。     

行进速度对搅拌摩擦加工高熵合金增强铝基复合材料组织与性能的影响

采用搅拌摩擦加工技术制备了FeCoNiCrAl高熵合金颗粒增强AA5083铝基复合材料,研究了行进速度(45,60,75 mm·min-1)对复合材料中高熵合金颗粒分布、显微硬度和耐磨性能的影响.结果表明:制备的复合材料中没有新相生成,复合材料的显微硬度高于铝合金基体的;随着行进速度的增加,高熵合金颗粒的分布均匀性变差,复合材料的显微硬度略微降低;复合材料的平均摩擦因数和磨损率均较铝合金基体的低;随着行进速度的增加,复合材料摩擦因数和磨损率均增大,耐磨性能下降;复合材料和铝合金的磨损机制分别为磨粒磨损和黏着磨损.     

高熵合金增强铝基复合材料组织与显微硬度研究

以5083铝合金为基体,以FeCoNiCrMn高熵合金颗粒为增强相,通过搅拌摩擦加工技术制备了颗粒增强铝基复合材料,研究了加工道次对复合材料微观组织和显微硬度的影响。研究结果表明:增加加工道次可以使得FeCoNiCrMn高熵合金颗粒在基体中分散更加均匀,显微硬度结果显示添加FeCoNiCrMn高熵合金颗粒后复合材料硬度得到大幅度提升,且5道次加工后的显微硬度最高。     

原位铝基复合材料搅拌摩擦加工工艺探索

搅拌摩擦加工是一种新型的原位铝基复合材料的研究方法。本文从搅拌摩擦加工的工艺参数、材料流变的组织分析方法和材料流变模型三个维度探索了该工艺在原位铝基复合材料组织性能的研究中的影响和作用。     

基于FSP技术制备CeO_2颗粒增强铝基复合材料

采用搅拌摩擦加工技术研究制备了CeO_2颗粒增强5083铝基复合材料,研究了加工道次对材料微观组织、显微硬度和磨损体积的影响。研究结果表明:CeO_2颗粒在基体中的分散程度随着加工道次的增加而增强;添加CeO_2颗粒可以提高材料的硬度和耐磨性,材料的显微硬度随着加工道次的增加而增加,3道次加工后的磨损体积最小。     

搅拌摩擦加工原位合成Al-Ti颗粒增强铝基复合材料的微观结构

采用搅拌摩擦加工法进行了原位合成Al-Ti金属间化合物颗粒增强铝基复合材料的试验,研究了复合材料的微观组织和精细结构。结果表明,以纯Ti粉和纯铝板为原材料,采用搅拌摩擦加工的方法可以原位合成TiAl3金属间化合物颗粒增强铝基复合材料。在复合材料铝基体上,除了生成的TiAl3金属间化合物外,还存在一些纯Ti颗粒以及纯铝基体上的固溶体。经旋转摩擦挤压后,纯铝基体的晶粒得到细化,尺寸为200nm左右,生成的TiAl3晶粒尺寸约为200~300nm。     

搅拌摩擦焊技术应用现状和发展趋势

文章对搅拌摩擦焊技术概况和技术特点进行了简要介绍,对搅拌摩擦焊技术在国内外的应用现状进行了分析,并预测了搅拌摩擦焊技术的发展趋势。文章认为,铝合金等轻金属连接是搅拌摩擦焊技术的主要应用领域。同时,在搅拌摩擦焊技术的基础上进行新技术（如表面改性、材料制备和搅拌摩擦点焊等）的开发,是该技术的一个很重要的发展趋势。     

分散剂对FSP制备IMC/Al复合材料组织与拉伸性能的影响

采用搅拌摩擦加工(FSP)技术制备了金属间化合物增强铝基(IMC/Al)复合材料,通过扫描电镜(SEM)、能谱仪(EDS)、X射线衍射仪(XRD)和拉伸试验机等研究了分散剂SiC和CNTs对复合材料组织的均匀性、增强相含量与尺寸及拉伸强度的影响。结果表明:通过FSP制备IMC/Al复合材料时出现镍粉团聚现象,团聚体的形状主要为类条形和类椭圆形;分散剂的添加对镍粉的团聚起到抑制作用,改善了复合材料复合区组织的均匀性,其中CNTs抑制镍粉团聚的效果优于SiC的;分散剂的添加促进了铝和镍原位反应的进行,使得复合材料中增强相Al3Ni的数量增多;分散剂的添加提高了复合材料的力学性能,添加CNTs制备复合材料的最大抗拉强度为171MPa,比未添加分散剂制备复合材料的提高了15.5%。     

Composite fabrication using friction stir processing—a review

Composite manufacturing is one of the most imperative advances in the history of materials. Nanoparticles have been attracting increasing attention in the composite community because of their capability of improving the mechanical and physical properties of traditional fiber-reinforced composites. Friction stir processing (FSP) has successfully evolved as an alternative technique of fabricating metal matrix composites. The FSP technology has recently shown a significant presence in generation of ex situ and in situ nanocomposites. This review article essentially describes the current status of the FSP technology in the field of composite fabrication with the main impetus on aluminum and magnesium alloys.     

In situ formation of Al–Al3Ni composites on commercially pure aluminium by friction stir processing

Possibility of the formation of Al–Al₃Ni composite layers on commercial pure aluminium plates by friction stir processing (FSP) has been studied. It is believed that the hot working nature of FSP can effectively promote the exothermic reaction between Al and added Ni powder to produce Al₃Ni intermetallic compounds in the aluminium matrix. In this study, the effects of the rotational and traverse speed of the tool as well as the number of FSP passes on the in situ formation of Al₃Ni in aluminum matrix were examined. Besides, the microstructure and microhardness of the fabricated surface layers were also studied. The results showed that the ratio of tool rotational speed to traverse speed (ω/υ) is the main controlling parameter of the heat generated during FSP and hence the reaction between aluminium and nickel. Increasing the number of FSP passes also promoted the reaction between Ni and Al and improved the distribution of Al₃Ni compounds, too. The composite layer achieved by six passes of FSP showed the highest hardness, which was almost twice of that of the base metal.     

Graphene Nanoplatelet (GNP)-Incorporated AZ31 Magnesium Nanocomposite: Microstructural,Mechanical and Tribological Properties

Graphene nanoplatelets (GNPs), despite their unique properties, were not widely investigated as reinforcement in metal matrix nanocomposites. The nanocomposite was fabricated by adding 15-nm-thick GNPs to AZ31 magnesium alloy via friction stir processing (FSP). Mechanical, frictional and wear properties were investigated. It was observed that refined microstructure with a range of 3–9 µm grain size and the presence of GNPs, i.e., reinforcing particles, improved the tensile properties and increased the ultimate tensile strength to 278 MPa. FSP increased the strain-to-fail by 133% compared to that of base metal, while it was decreased by adding GNPs. Moreover, the presence of GNPs decreased the adhesive wear mechanism by squeezing out, smudging on the surface and, finally, forming a protective layer between the sliding surfaces. Hence, the coefficient of friction was decreased to 60% and the range of fluctuations in friction plot was confined by adding GNPs. They were further decreased by increasing the normal load and sliding velocity due to easier debonding of the GNPs and the surrounding AZ31 Mg matrix resulting in forming a lubricating layer between sliding surfaces.     

Modification of electrical conductivity by friction stir processing of aluminum alloys

A wide range of solid-state manufacturing technologies for joining and modification of material original properties are assuming increasing importance in industrial applications. Among these, friction stir-based technologies are the most significant, namely, friction stir processing (FSP) and friction stir surfacing. The electrical conductivity is a significant property undergoing modification, but this property has not been characterized and fully exploited from the technological point of view. The present work aims to study the electrical conductivity behavior in FSP of aluminum alloys in order to identify the major factors governing this property. FSP was applied on AA1100, AA6061-T6, and AA5083-H111 alloys with different parameters. Electrical conductivity profiles were measured at different depths and compared with hardness profiles and microstructures. It was found that solid-state friction stir processing of aluminum alloys lead to electrical conductivity changes of about 4%IACS (International Annealed Copper Standard). These changes are more intense in heat-treatable alloys than in work-hardenable ones. Higher rotating versus travel speed ratios (??/V) induce higher variations in the electrical conductivity. In FSP, the factors governing the electrical conductivity variations are mostly the grain size and the presence of precipitates. It was shown that, for some FSP applications, electrical conductivity may be a process characterization method more precise and meaningful than hardness to assess local material condition.     

纳、微米Al2O3颗粒混杂增强铝基复合材料的磨损性能

利用搅拌摩擦加工(FSP)制备纳、微米氧化铝颗粒单一增强以及混杂增强的A356铝基复合材料,并在摩擦磨损试验机上考察其磨损性能。结果表明,在0.5~3.0 MPa载荷范围内,在相同载荷下,混杂复合材料的磨损量都低于两种单一增强的复合材料;在不同载荷下,随着载荷的增加,复合材料的磨损量都增加,但是混杂颗粒增强复合材料的增加最快,微米颗粒增强复合材料最慢;复合材料的磨损机制主要是磨粒磨损和剥层磨损;在复合材料磨损亚表层都发现机械混合层的存在,对复合材料的耐磨性有一定的影响。     

Influence of FSP on the microstructure,microhardness, intergranular corrosion susceptibility and wear resistance of AA5083 alloy

This article investigates the role of friction stir processing (FSP) process parameters on the evolution of microstructure, hardness, intergranular corrosion resistance and wear resistance of aluminium alloy AA5083. The FSP trials are performed by changing the process parameters as per face-centered central composite design. The friction stir processed (FSPed) specimens subjected to intergranular corrosion test and wear test are characterized using field emission scanning electron microscope, energy dispersive x-ray spectroscopy and X-ray diffraction. Outcomes suggest that grain refinement, dispersion and partial dissolution of secondary phase has simultaneously increased the hardness, intergranular corrosion resistance and wear resistance of the FSPed specimens. The study found that tool rotation speed of 700?rpm, tool traverse speed of 60?mm?min^?1 and shoulder diameter of 15?mm results in maximum hardness, wear resistance and intergranular corrosion resistance.     

Sensitization resistance of friction stir welded AISI 409?M grade ferritic stainless steel joints

Friction stir welded low chromium AISI 409?M ferritic stainless steel was investigated for susceptibility to intergranular corrosion by oxalic and double-loop electrochemical potentiodynamic reactivation tests, and the degree of sensitization were evaluated by the ratio of the reactivating and activating currents. Stir zone of friction stir welded joint exhibited smaller degree of sensitization compared to the base metal and it is mainly due to fine grains and lower heat input nature of friction stir welding process. Heat-affected zone showed larger current ratio and higher degree of sensitization compared to stir zone and base metal region and not to the extent that has been reported in the literature for arc welding.     

Mechanical properties of graphite/aluminum metal matrix composite joints by friction stir spot welding

Graphite/aluminum metal matrix composite (MMC) joints are successfully fabricated by friction stir spot welding (FSSW). During lap-joining processes of aluminum alloy sheets by FSSW, graphite/water colloid is applied between the tool shoulder and the upper plate. The Raman spectrum of the FSSW joint confirms that graphite/aluminum MMC is successfully induced in the stir zone. Quasi-static shear tests and micro hardness measurements of the FSSW joint also show that the strength and toughness of the joint are significantly improved by inducing graphite/aluminum MMC in the stir zone. The results of the present study suggest that the mechanical properties of structural components joined by spot welds can be easily enhanced by adopting MMC joints by FSSW, instead of changing the material or increasing the number of joints.