冷压烧结-热挤压复合工艺制备亚微米SiC_P/Cu复合材料的力学及耐磨性能

采用冷压烧结-热挤压复合加工工艺制备了亚微米SiC颗粒增强铜基复合材料,研究了SiC_P/Cu复合材料的微观组织、显微硬度、力学性能、导电性能和耐磨性能。结果表明:采用本方法可以获得组织致密的亚微米SiC颗粒增强Cu基复合材料。复合材料5vol%亚微米SiC_P/Cu复合材料展现出了优良的耐磨性能,是锡青铜的1.7~8倍。在复合材料磨损表面形成了高硬、SiC颗粒弥散均匀的耐磨损层。     

SiCp在Mg-Zn-Ca-Mn复合材料的力学性能及微观结构的影响

在目前的研究中,利用搅拌铸造结合超声处理方法成功的制备出了不同体积分数（5 和10 vol.%）的微米颗粒增强的AZ31B镁基复合材料。利用350℃,12:1的挤压比对铸锭进行了挤压处理。利用金相和扫描电子显微镜两种不同体积分数的SiCp被选做为增强体,利用半固态结合超声处理法制备了Mg-Zn-Ca-Mn复合材料,然后在350℃用15:1的挤压比进行了热挤压。利用OM、SEM和TEM对材料的微观结构进行了检测。热挤压后的微观结构显示SiC颗粒的分布较为均匀且在1vol.% SiCp/Mg-Zn-Ca-Mn 和 3vol.% SiCp/Mg-Zn-Ca-Mn复合材料中晶粒被显著细化。SiCp的引入可以改善0.2%屈服强度和抗拉强度。屈服强度和抗拉强度是随着颗粒含量的增加而增加。     

不同凝固压力条件下A356-10%SiC复合材料的微观组织及性能

通过搅拌法制备A356?10%10SiC复合材料,并分别在0.1(重力条件)、25、50和75 MPa压力条件下进行该复合材料的直接挤压铸造成形,研究了铸态和 T6热处理后复合材料的微观组织及力学性能。结果表明：随着挤压力的增大,铸件的增强颗粒?孔洞团簇缺陷减少,并改善了增强颗粒与基体间的结合强度,拉伸强度、硬度和热膨胀系数增加。与铸态复合材料相比,T6热处理后复合材料的抗拉强度和硬度增大而热膨胀系数减小;在重力条件下凝固的复合材料断口处存在增强颗粒?孔洞团簇缺陷,而在挤压力下凝固的复合材料断口未观察到该缺陷,断口特征表明两者存在不同的断裂机制。     

等径角挤压层状复合材料的扩散连接（英文）

研究了等径角挤压层状复合材料的微观组织、扩散和机械结合行为以及显微硬度分布。在室温和高温(300°C)下采用1～4道次等径角挤压工艺制备Al-Cu和Cu-Ni层状复合材料。扫描电镜微观结构表征及抗剪强度试验结果表明,由于在等径角挤压过程中具有更高的塑性变形容忍度,4道次等径角挤压试样层片材料之间的结合强度远远高于1道次样品。此外,剪切强度数据表明,升高等径角挤压温度会使试样的剪切强度显著增加,这主要是由于Al/Cu和Cu/Ni界面在高温下形成了扩散连接。等径角挤压Cu/Ni/Cu复合材料的高温剪切结合强度明显高于等径角挤压Cu/Al/Cu复合材料。     

微米级SiC颗粒增强铝基复合材料的强化机制

为了研究微米级碳化硅颗粒(SiCp)尺寸和含量对中体积分数SiCp增强铝基复合材料强化机制的影响,用粉末冶金工艺制备SiCp体积分数为30%~40%,颗粒尺寸为3~40μm的SiCp/2024Al复合材料,利用TEM,万能材料试验机等对材料微观结构和拉伸性能进行了研究。结果表明,复合材料的抗拉强度和硬度均随着SiC颗粒尺寸的增大而减小,随体积分数的增加而增大。复合材料的强化是由多种强化机制协同作用的结果,SiC颗粒尺寸主要通过位错强化和细晶强化显著影响对复合材料的强化效果。     

SiCp对Mg-Zn-Ca-Mn复合材料的力学性能及微观结构的影响（英文）

2种不同体积分数的SiCp被选作为增强体,利用半固态结合超声处理法制备了Mg-Zn-Ca-Mn复合材料,然后在350℃用15:1的挤压比进行了热挤压。利用OM、SEM和TEM对材料的微观结构进行了检测。热挤压后的微观结构显示SiC颗粒的分布较为均匀且在1vol%SiCp/Mg-Zn-Ca-Mn和3vol%SiCp/Mg-Zn-Ca-Mn复合材料中晶粒被显著细化。SiCp的引入可以改善屈服强度和抗拉强度。屈服强度和抗拉强度是随着颗粒含量的增加而增加。     

原位TiB2颗粒增强铝基复合材料及其力学性能

对原位反应合成TiB2／A356铝基复合材料微观组织和力学拉伸性能进行了研究。结果表明，原位反应生成的颗粒增强相在复合材料基体中分布均匀，基体与颗粒间的界面洁净。复合材料强度随着颗粒含量的增加显著提高，与基体合金相比，TiB2质量分数为8％的TiB2／A356复合材料强度和弹性模量的提高幅度约为28％，TiB2质量分数为16％的TiB2／A356复合材料强度和弹性模量的提高幅度约为35％。复合材料的断裂主要是由于基体与颗粒界面脱粘，在拉伸应力作用下由此萌生微裂纹并扩展，导致界面处的基体撕裂，从而降低复合材料塑性。     

碳纤维含量对碳纤维增强PE复合材料力学性能的影响

以短切碳纤维为增强体,以聚乙烯树脂为基体,运用螺杆注射成型的方法制备碳纤维增强热塑性复合材料.研究了碳纤维含量对复合材料硬度、拉伸、疲劳等性能的影响.结果表明,随着碳纤维含量的增加,复合材料的维氏硬度呈S形增加,拉伸强度、弹性模量、条件疲劳极限值都有提高;当碳纤维含量为4.021％时,相对纯聚乙烯,硬度、拉伸强度、弹性模量、条件疲劳极限值分别增加了35.489％、18.421％、208.024％、213.240％     

K2O·6TiO2(w)/ZA-27复合材料显微组织与性能

采用挤压铸造法制备了Ｋ２Ｏ·６ＴｉＯ２晶须增强ＺＡ－２７合金复合材料,分析了复合材料的显微组织特性,利用ＴＥＭ对该复合材料界面的微观结构进行了观察与分析,测试了复合材料的抗拉强度和硬度。实验结果表明：该复合材料渗透完全,晶须分布均匀,观察有两种形态界面存在,复合材料的硬度随晶须含量的增加而显著提高。     

SiC纳米颗粒增强A356铸造合金的表征(英文)

通过搅拌铸造制备SiC纳米颗粒增强A356铝合金复合材料,并研究其显微组织和力学性能。密度测量发现试样的孔隙度较低,且孔隙度随SiC颗粒体积分数的增加而增加。通过光学显微镜和透射电镜观察材料的显微组织,发现弥散的颗粒分布均匀。材料的拉伸强度和弹性模量随加入纳米SiC颗粒的增加而提高,而延展性有所降低。当SiC纳米颗粒的加入量为3.5%时,复合材料的屈服强度和极限抗拉强度达到最高。断口分析表明,拉伸断裂试样为相对韧性断裂。     

Tensile and wear properties of rolled Al5Mg-Al<Subscript>2</Subscript>O<Subscript>3</Subscript> or C particulate composites

Al5Mg alloy matrix composites reinforced with different percentages of Al₂O₃ (60 μm) or C (90 μm) particulates were prepared by the vortex method. The composites were then subjected to hot or cold rolling with different reduction ratios. The microstructures of the rolled composites revealed that the matrix grains moved around the particulate causing deformation. By continuing deformation, the particulates rearranged themselves in the matrix, leading to lensoid distortion. It was found that the addition of Al₂O₃ or C particulates increased the 0.2% proof stress and reduced both the tensile strength and ductility, compared with the monolithic alloy. Scanning electron microscopy (SEM) fractographic examinations showed that the composites reinforced with Al₂O₃ particulates failed through particulate fracture and matrix ligament rupture. However, the failure of the composites reinforced with C particulates was through particulate decohesion, followed by ductile failure of the matrix. Abrasive wear results showed that the wear rate of the Al5Mg alloy decreased with the addition of C particulates. However, increasing the volume fraction of C particulates did not have a prominent effect on the wear rate. The composites reinforced with Al₂O₃ particulates exhibited a higher wear rate than that of the unreinforced alloy. Furthermore, addition of both C and Al₂O₃ particulates into the Al5Mg matrix alloy did not significantly improve the wear resistance. For all composites studied in this work, hot or cold rolling had a marginal effect on the wear results.     

Microstructure and damping behavior of SiCp/Gr/2024Al metal matrix composites by squeeze casting technology

SiCp/Gr/2024Al metal matrix composites were processed by squeeze casting technology. The microstructure of composites was observed by SEM and TEM, and the effects of graphite particulates and SiC particulates on the damping behaviors of composites were also investigated. The results show that the microstructure of composites was dense and homogeneous, without any interfacial reactivity among reinforcement/matrix interfaces. Compared with the damping capacity of 2024Al, the damping capacity of composites was enhanced significantly by addition of SiC or graphite particulates. The main damping mechanisms of SiCo/Al composites were ascribed to the dislocation damping, and those of SiCo/Gr/2024Al were attributed to the intrinsic damping and interface damping.     

原位TiC颗粒增强Fe—Cr—Ni基复合材料的高温蠕变行为

在973－1123K和40－160MPa条件下研究了含5％,10％,16％（体积分数,下同）原位TiC颗粒增强的Fe-26Cr-14Ni基复合材料的高温蠕变性能,原位TiC颗粒明显改善了Fe-26Cr-14Ni基复合材料的高温蠕变性,含5％和10％TiC复合材料的抗蠕变能力比基础合金增强,随着TiC颗粒体积分数的增高,复合材料的蠕变速率降而蠕变激活能和临界应力提高,TEM显微组织观察表明,复合材料的蠕变主要是以局部位错攀移机制进行的,因此,所有蠕变速率可以由应力指数为5的指数方程经归一化处理得到。     

Microstructure and mechanical properties of Alborex+SiCp/AS52 hybrid metal matrix composites

Abstract

AS52 based hybrid composites reinforced with aluminium borate whiskers and SiC particulates were fabricated by a squeeze casting method. In a hybrid preform, the volume fraction of the aluminium borate whisker was 15% and that of the SiC particulate was 5%. Microstructures of the specimens were observed using OM and SEM. In the hybrid composites, the Alborex whiskers were uniformly distributed in the matrix and a few agglomerations or clusters of SiC particulates were observed. Hardness and three point bending tests were carried out to measure the mechanical properties of the specimens. The mechanical properties of the hybrid composites were higher than those of whisker reinforced composites and the hybrid composite with finer size particulates showed higher strength than the one with coarse particulates.     

Influence of Al2O3 or ZrO2 particulate addition on the microstructure aspects of AlNi and AlSi alloys

Different metal/ceramic composites (Al7Si0.3Mg, Al3Ni, Al6Ni, Al9Ni) reinforced with Al₂O₃ or ZrO₂ were prepared by vortex method. Metallographic investigations reveal that in all the composites -Al did not nucleate on the reinforcement particulates. The particulates were generally observed to be located in the last freezing regions regardless of matrix alloy, particulate type or size. The reason for that was the mismatch in the thermal diffusivity between the ceramic particulates and matrix alloys. SEM micrographs show that the presence of the particulates in the AlSi alloy tends to modify the silicon eutectic. In contrast, the addition of the particulates into AlNi alloys did not result in a significant modification of the NiAl₃ phase, but it displaced the eutectic point to lower Ni content.     

SiCp/Al复合材料的离心熔渗法制备及其性能

研究了反应离心熔渗法制备高体积比SiCp／Al复合材料的工艺过程及其抗弯强度。结果表明：通过适当的粒度配比，可在低温、低离心力下熔渗制备组织均匀的高体积比SiCp／Al复合材料，SiC颗粒体积分数可达到63％；复合材料的强度在很大程度上依赖于SiC颗粒尺寸及界面反应程度，合适的界面结合及细SiC颗粒的掺入有利于复合材料强度的提高；基体热处理改变了SiC颗粒所受应力状态，提高了复合材料的强度，其最高值可达519MPa。     

Microstructure characterization of reinforcements in in-situ synthesized composites of Al-Zr-O system

A novel in-situ reaction system Al-Zr-O was developed. In-situ Al3Zr and Al2O3 particulates reinforced aluminum matrix composites were fabricated by the direct melt reaction technique in the Al-Zr-O system. Microstructures of the composites and crystal morphology of in-situ formed Al3Zr and Al2O3 particulates were analyzed by scanning electron microscope (SEM) and transmission electron microscope (TEM). Results indicate that in-situ formed Al3 Zr and Al2O3 particles are finer and well distributed in aluminum matrix. Al3Zr particulates with a tetragonal structure are mainly in the shape of polyhedron. A few of them are in the form of rectangle. The length/width ratio of the rectangular Al3Zr is less than 2.0 and the maximum size is 2μm. In addition, a certain number of Al2O3 submicro particles with a hexagonal structure are also generated in this system. Furthermore, it is found that Al3Zr crystal grows by the mechanism of twinning. The twin plane is (114). The twinning direction is [221]. The tensile tests show that the composites synthesized in the Al-Zr-O system exhibits high strength and ductility. There are a lot of ripples with fine particles on the fracture. The principal strengthening mechanisms for (Al3Zr Al2O3 )p/Al composites may include Orowan strengthening, grain-refining strengthening, solid-solution strengthening and dislocation strengthening.     

原位TiB2亚微米颗粒增强铝基复合材料的高温蠕变性能

运用盐-金属反应法制备了亚微米TiB2颗粒增强铝基复合材料（TiB2/AC8A）.TiB2颗粒通过钛盐和硼盐与铝合金反应原位生成.对复合材料进行了显微组织观察和高温蠕变性能实验.原位TiB2颗粒的尺寸约为0.5μm,近似呈球形。TiB2／AC8A复合材料具有优异的高温蠕变性能。10ω／％TiB2原位颗粒（～0．5μm）增强AC8A复合材料的蠕变抗力比10φ／％SiCp（1．7μm）外加颗粒增强AI复合材料至少要高两个数最级。10ω／％TiB2／AC8A复合材料表现出高的名义应力指数（11．7～12．5）和名义激活能（265kJ／mol），其稳态蠕变数据能够用廊力指数为8的亚结构不变模型和门槛应力来解释。TiB2／AC8A复合材料的蠕变断裂行为符合Monkman-Grant关系式。     

Interface and microstructure characteristics of SiC_p/2024 aluminium alloy composite

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速度和压力对SiCp增强铝基复合材料摩擦磨损性能的影响

研究了颗粒增强铝基复合材料及其基体的摩擦磨损性能。基体和复合材料的耐磨性有明显差异，复合材料的主要磨损形式是磨粒磨损，基体材料的主要磨损形式是粘着磨损。复合材料具有低的磨损率和稳定的摩擦因数，因此具有良好的耐磨性。