异种金属层状复合材料累积叠轧工艺的研究进展

综述了异种材料累积叠轧技术,介绍了累积叠轧的工艺原理及异种材料累积叠轧试样的宏观结构和力学性能研究进展,分析了层状复合材料累积叠轧工艺的复合机理和强化机制,最后展望了异种材料累积叠轧工艺的应用和发展并对进一步的研究提出了建议。     

非连续增强金属基复合材料剧烈塑性变形行为研究进展

综述了非连续增强金属基复合材料剧烈塑性变形(SPD)行为的研究进展,系统阐述了等径弯曲通道变形(ECAP)、高压扭转(HPT)、多向锻造(MF)、累积叠轧(ARB)和循环挤压压缩(CEC)5种SPD的加工原理和方法。集中介绍了这些方法在铝基、镁基、铜基和钛基等金属基复合材料方面应用的研究进展。重点介绍了金属基复合材料SPD的微观组织演化和变形力学行为,详细阐明了金属基复合材料SPD机制以及超细晶形成机理,指出了金属基复合材料在SPD中存在的深层次问题及发展趋势,展望了利用SPD方法制备超细晶非连续增强金属基复合材料的应用前景。     

累积叠轧技术研究进展

大塑性变形工艺是制备超细晶材料的主要成形技术.其中,累积叠轧(ARB)因工序简单、成本低,对模具要求低,可连续生产大尺寸的细晶板材,而获得广泛应用.从累积叠轧后材料的组织特性、力学性能以及强化机制和界面结合机制方面梳理国内外累积叠轧工艺的研究现状.提高累积叠轧材料的塑性极其重要.制备高强度、高塑性ARB复合材料将成为后续研究热点.     

累积叠轧焊过程中的材料界面焊合

累积叠轧焊(ARB)工艺可以制备超细晶、高性能、大尺寸的金属及合金板材,具有自身突出的优越性,容易实现工业化生产,是目前剧塑性变形工艺领域的研究热点之一。ARB变形金属层间的界面焊合强度是影响其工艺及材料工业应用的主要因素之一。本文对累积叠轧焊工艺的界面焊合特点进行了综述,对道次变形量、ARB变形前后退火工艺、板材表面处理等因素对ARB板材界面焊合性能的影响进行深入分析。同时简要介绍了板材界面焊合质量的表征方法。     

颗粒增强金属基复合材料涂层的制备及其特性与应用

针对复合材料涂层的相关问题, 综述了颗粒增强金属基复合材料涂层的制备技术及其特性的研究进展。重点描述了电热爆炸超高速喷涂技术及电刷镀技术制备颗粒增强金属基复合材料涂层的发展现状、涂层组织结构和力学性能研究进展, 概述了颗粒增强金属基复合材料涂层的工程应用领域及其未来发展方向。     

AZ31镁合金在累积叠轧焊过程中的界面焊合研究

采用扫描电境观察了AZ31镁合金在累积叠轧焊(ARB)过程中的界面焊合现象。结果表明:轧前预热温度为300℃和道次压下量为50%的累积叠轧焊工艺可以使AZ31板材获得良好的界面焊合,后续的累积叠轧焊变形可以有效改善界面焊合质量。ARB板材的拉伸断口呈现典型的延性断裂形貌,界面未形成良好焊合的部分呈现裂口焊合形貌。累积叠轧焊变形中的界面焊合过程包括:表面硬化脆性层减薄、断裂,氧化膜破碎,暴露出来的新鲜金属在轧制压力的作用下沿裂纹流动、相互接触,形成冶金结合。后续退火可以改善界面焊合质量。     

轧制三金属复合材料研究进展

三金属层状复合材料兼具了各金属组元的优势,能够满足多种复杂服役环境的应用需求,是现代科学技术进步的必然产物.将最为常见的轧制制备的三金属层状复合材料根据具体制备手段和最终实验效果的差异,分为了采用新型累积叠轧技术制备的类双金属颗粒增强金属基复合材料,以及利用常规轧制减薄技术制备的三金属层状复合材料.分别综述了这两大类目前主要的组合类型及其涉及的研究内容,可看出众多研究均是在最为原始的二元Al/Cu和Al/Mg复合基础上新加第三金属展开的.指出了三金属复合材料的开发是未来金属层状复合材料领域的重要研究方向,以及后续有待进一步解决的难点.最后,对三金属层状复合材料的发展前景和主要发展方向进行了展望.     

喷射沉积成形颗粒增强金属基复合材料制备技术的发展

分析了喷射沉积成形颗粒增强金属基复合材料制备技术的研究现状。系统地介绍了原位反应喷射沉积成形过程中进行的各类反应。在总结国内外喷射沉积成形颗粒增强金属基复合材料制备技术优缺点的基础上,发展了熔铸－原位反应喷射沉积成形金属基复合材料制备新技术。     

粉末冶金法制备碳纳米管增强金属基复合材料研究进展

粉末冶金法具有工艺灵活,可设计性强等特点,是制备碳纳米管增强金属基复合材料的重要制备方法之一。简述了粉末冶金工艺制备金属基复合材料的流程和工艺特点,枚举若干实例总结了粉末冶金法制备碳纳米管增强金属基复合材料的性能特点,以及国内外研究现状,展望了该类材料未来发展前景。     

选区激光熔化制备颗粒增强金属基复合材料的研究进展

选区激光熔化是一种使用聚焦高能激光束熔化粉末,逐层叠加成形零件的增材制造方法.选区激光熔化可以直接制备复杂结构零件和实现近净成形,能够方便地通过粉末预混添加或原位反应实现颗粒增强金属基复合材料的控形控性,具有独特的技术优势,受到广泛关注.本文综述了选区激光熔化制备颗粒增强金属基复合材料的研究进展,总结了主要研究结果及存在的共性问题,并展望了选区激光熔化制备颗粒增强金属基复合材料的研究方向和发展趋势.通过总结分析,指出选区激光熔化制备颗粒增强金属基复合材料时,聚焦激光作用下形成的高温微小熔池凝固时间短,远远偏离平衡状态,凝固过程复杂,增强颗粒与基体间冶金反应剧烈,容易熔化、分解和溶解并对基体特性产生影响,进而影响成形后的复合材料的宏观形貌和组织、性能.除增强体成分、颗粒形貌与尺寸、体积分数外,复合材料的性能还受激光功率、扫描速度、扫描间距、粉层厚度、成形气氛等工艺参数的影响,粉末特性与工艺参数之间的交互作用复杂.因此,考察工艺参数与粉末特性之间的交互作用关系,系统研究增强体颗粒特性与成形工艺参数对复合材料宏观形貌、致密度、缺陷、组织和性能的影响规律,是实现复合材料组织结构设计和性能调控的基础.     

Production of high strength Al-Al2O3 composite by accumulative roll bonding

Recently accumulative roll bonding has been used as a novel method to produce particle reinforced metal matrix composites. In this study, aluminum matrix composite reinforced by submicron particulate alumina was successfully produced and the effects of number of ARB cycles and the amount of alumina content on the microstructure and mechanical properties of composites were investigated. According to the results of tensile tests, it is shown that the yield and tensile strengths of the composite are increased with the number of ARB cycles. Scanning electron microscopy (SEM) reveals that particles have a random and uniform distribution in the matrix by the ARB cycles and a strong mechanical bonding takes place at the interface of particle-matrix. It is also found that the tensile strength of the composite, as a function of alumina content, has a maximum value at 2 vol.%, which is 5.1 times higher than that of the annealed aluminum.     

Evaluation of mechanical properties of 1060-Al reinforced with WC particles via warm accumulative roll bonding process

In the present study, aluminum metal matrix composites (AMMCs) reinforced with tungsten carbide (WC) particles are manufactured through warm accumulative roll bonding (ARB). The composite microstructure shows excellent WC particle distribution in the Al matrices, and no reaction between Al and WC is observed. Compared with the ARBed 1060-Al, the Al/WC composites show a higher number of dislocations, as suggested by the introduction of WC particles. The tensile, hardness, and wear properties of the Al/WC composites are determined. The introduction of 3 vol% WC particles to the Al matrix via the warm ARB process leads to significantly enhanced mechanical properties.     

Refinement of microstructure and improvement of mechanical properties of Al/Al2O3 cast composite by accumulative roll bonding process

Some important problems associated with cast metal matrix composites (MMCs) include non-uniformity of the reinforcement particles, high porosity content, and weak bonding between reinforcement and matrix, which collectively result in low mechanical properties. Accumulative roll bonding (ARB) process was used in this study as a very effective method for refinement of microstructure and improvement of mechanical properties of the cast Al/10 vol.% Al₂O₃ composite. The average particle size of the Al₂O₃ was 3 μm. The results revealed that the microstructure of the composite after eleven cycles of the ARB had an excellent distribution of alumina particles in the aluminum matrix without any noticeable porosity. The results also indicated that the tensile strength and elongation of the composites increased as the number of ARB cycles increased. After eleven ARB cycles tensile strength and elongation values reached 158.1 MPa and 7.8%, which were 2.54 and 2.36 times greater than those of the as-cast MMC, respectively.     

Fabrication and evaluation of nanostructure Al-SiCp composite by accumulative roll-bonding

A nanostructured Al/SiCp composite was fabricated by accumulative roll bonding (ARB) process. The amount of SiC particles introduced into aluminum sheet by one cycle ARB was 0.22 mg/cm2. Increment of the number of ARB cycles increased the amount of SiC particles and enhanced the homogeneity of the distribution of SiC particles. Microstructural change in aluminum matrix with proceeding of the ARB was very similar to that of the ARB-processed unreinforced aluminum; showing a dislocation cell and/or sub-grain structure in samples of lower ARB cycles and ultrafine grained structure in samples of higher ARB cycles. The variation of tensile strength with the ARB was also very similar to that of unreinforced aluminum. However, the effect of strengthening by the ARB was higher in the Al/SiCp composite than in unreinforced aluminum due to an existence of the SiC particles and the formation of finer grains.     

Evolution of reinforcement distribution in Al–B4C composites during accumulative roll bonding

The distribution of reinforcement particles in the matrix of a composite is one of the most important microstructural features affecting properties. In this study, nanostructured Al–B₄C composite sheets were processed by accumulative roll bonding (ARB), and the effect of the number of ARB cycles on the distribution of the B₄C particles in the Al matrix was evaluated. From optical microscopic studies accompanied by the radial distribution function analysis, it was realized that the microstructure uniformity is improved by increasing the number of ARB cycles. It was in good agreement with bulk hardness measurements in which the standard deviation of the hardness values was decreased by progression of the ARB process. In addition, the X-ray diffraction peak profile analysis revealed that the area weighted mean crystallite size of the Al matrix decreases to the nanometric scale (114 nm) after seven ARB cycles.     

Evaluation of microstructure and mechanical properties of Al/Al2O3/SiC hybrid composite fabricated by accumulative roll bonding process

In this investigation, a new kind of metal matrix composites with a matrix of pure aluminum and hybrid reinforcement of Al₂O₃ and SiC particles was fabricated for the first time by anodizing followed by eight cycles accumulative roll bonding (ARB). The resulting microstructures and the corresponding mechanical properties of composites within different stages of ARB process were studied. It was found that with increasing the ARB cycles, alumina layers were fractured, resulting in homogenous distribution of Al₂O₃ particles in the aluminum matrix. Also, the distribution of SiC particles was improved and the porosity between particles and the matrix was decreased. It was observed that the tensile strength of composites improved by increasing the ARB passes, i.e. the tensile strength of the Al/1.6 vol.% Al₂O₃/1 vol.% SiC composite was measured to be about 3.1 times higher than as-received material. In addition, tensile strength of composites decreased by increasing volume fraction of SiC particles to more than 1 vol.%. Scanning electron microscopy (SEM) observation of fractured surfaces showed that the failure mechanism of broken hybrid composite was shear ductile rupture.     

Microstructure evolution and mechanical properties in ultrafine grained Al/TiC composite fabricated by accumulative roll bonding

In this study, the influence of nano-TiC particle on microstructure development and mechanical properties of Al/TiC composite fabricated by accumulative roll bonding (ARB) was considered to investigate. Microstructural characterization by electron backscatter diffraction (EBSD) system proved that the grain size decreased to around 200 nm and the TiC reinforcement particles were uniformly distributed in the Al matrix by 7-cycle of the ARB process. It is also found that presence of the TiC particles could accelerate grain refinement. Uniaxial tensile test exhibited that yield and ultimate tensile strength significantly improved more than four times in the 7-cycle ARB processed Al/TiC composite compared with the annealed aluminum specimen which used as the starting material. In addition, the obtained results demonstrated that adding the TiC reinforcement particles could improve the yield strength of the 7-cycle ARB processed Al sheet about 40 percentage.     

Comparison of microparticles and nanoparticles effects on the microstructure and mechanical properties of steel-based composite and nanocomposite fabricated via accumulative roll bonding process

In the present work, a comparison of microparticles and nanoparticles effects on the microstructure and mechanical properties of steel-based composite and nanocomposite fabricated via accumulative roll bonding (ARB) process was studied. The microstructure of the fabricated composite and nanocomposite after fourth cycle of the ARB process exhibited an excellent distribution of SiC micro/nano particles in the IF steel matrix without any porosity. Unlike the nanocomposite, the particle breaking (cracking) was one of the most important phenomena that occurred during ARB process of composite. The findings revealed that with increasing the number of ARB cycles, the tensile strength of the ARB-processed composite and especially nanocomposite improved, but their elongation decreased at first step and then increased at second step. In addition, the ARB-processed composite and especially nanocomposite exhibited a higher hardness than the annealed IF steel so that the hardness values of the composite and nanocomposite were 4.18 and 4.44 times higher than that of the annealed IF steel, respectively.     

An alternative method for manufacturing high-strength CP Ti–SiC composites by accumulative roll bonding process

For the first time, the accumulative roll bonding (ARB) process was used as an effective alternative method for manufacturing Ti–SiC composites and compared with the monolithic ARBed Ti. High-strength monolithic commercially pure titanium (CP Ti) and CP Ti–SiC composites with effective uniform reinforcement distribution were fabricated by this process. The tensile test, Vickers hardness measurements and SEM observations were done for the characterization of materials. A significant increase in yield and tensile strength and a drastic decrease in elongation were observed by applying 8 cycles of ARB process. An unexpectedly slight decrease of yield and tensile strength along with elongation was observed after the sixth ARB cycle for the monolithic sample. It was attributed to the weakening of the bond between the titanium layers in the final cycles. Strength of the composite samples was higher than that of the monolithic sample and did not decrease in the final ARB cycles. This was caused by the significantly improved distribution of SiC particles in the titanium matrix.     

Influence of carbide reinforcements on accumulative roll bonded Al 8011 composites

Numerous methods are available to produce ultrafine grained material in severe plastic deformation (SPD) techniques. Accumulative roll bonding (ARB) is the most effective techniques to produce ultrafine grained composites with superior properties. The present investigation deals with the fabrication and comparison of Al 8011 composite by introducing various reinforcements such as Titanium carbide (TiC), Tungsten carbide (WC), Boron carbide (B4C) and Zirconium carbide (ZrC) through ARB technique by deforming plastically. Here, four specimens were prepared by incorporating 8 wt.% each of aforementioned carbide particles in Al matrix and compared with each other and characterized through advanced microscopic techniques such as SEM, EDAX, EBSD and TEM besides XRD. Furthermore, Vickers microhardness test and tensile test were conducted. The introduced reinforcement particles were found dispersed evenly throughout the surface by increasing the passes up to eight times. Among these reinforcements, Al 8011 – B4C composite has provided better strength than other composites due to following reasons: (i) high bonding of the interface between the sheets (ii) interlocking of B4C particles within the matrix (iii) higher hardness and strength. Hence, B4C reinforced Al composite claims greater significance for being recommended as an effective alternative for the aluminum material in load carrying applications.