原位自生A356/TiB2复合材料的组织与性能

通过混合盐法制备了原位自生TiB2颗粒增强A356复合材料.扫描电镜观察结果表明,制备的原位自生TiB2颗粒分布均匀,其最大尺寸在500nm左右,平均尺寸在200nm左右.高分辨透射电子显微镜观察结果表明,颗粒与基体之间界面结合良好、干净,无任何杂质相的存在.复合材料的抗拉强度和屈服强度较基体都有了明显提高;复合材料的阻尼性能明显高于基体合金的阻尼性能,其室温时的数值为0.018.该研究成功地实现了材料力学性能和阻尼性能的同时提高.     

放电等离子烧结合成TiC/TiB_2颗粒增强的超细晶钛基复合材料

采用放电等离子烧结技术结合非晶晶化法制备了不同体积分数的TiC/TiB2颗粒增强的超细晶钛基复合材料.运用X射线衍射分析、扫描电子显微镜和万能材料试验机等实验手段,对合成的超细晶钛基复合材料进行测试分析.结果表明：随着外加TiC/TiB2颗粒的增加,钛基复合材料试样的致密度逐渐降低.TiC颗粒与基体不发生反应,而TiB2颗粒的加入改变了TiB2颗粒与基体界面的组织形貌,但对远离界面处的基体组织形貌没有影响,其组织均由-Ti（Nb）相和（Cu,Ni）-Ti2相组成,且-Ti（Nb）相连续分布.同时,TiC颗粒的增强效果优于TiB2颗粒,35vol.%（体积分数）TiC颗粒增强的复合材料试样的断裂强度最高,达2209MPa.     

(TiB_2+Al_2O_3)增强铝基复合材料的制备工艺

将TiO2和B2O3原料混合后加入铝熔体,采用原位反应的方法,使其与铝液发生反应,制备出(TiB2+Al2O3)双相增强铝基复合材料.研究反应物加入量、反应时间、搅拌强度对复合材料的组织形貌产生的影响.结果表明,反应物加入体积分数为20%,反应时间为20 min,较大搅拌强度条件下原位生成的增强颗粒明显增多,晶粒细小,分布均匀.     

(TiB_2+Al_2O_3)增强铝基复合材料的组织分析与硬度测试

将TiO2和B2O3原料混合后加入ZL102铝熔体,采用原位反应的方法,使其与铝液发生反应,制备出(TiB2+Al2O3)双相增强铝基复合材料.用EPMA及SEM分析反应合成的增强颗粒在基体上的分布状态以及TiB2和Al2O3颗粒的微观组织,用显微硬度仪测定复合材料组成相的显微硬度.结果表明,利用Al-TiO2-B2O3体系可以原位制备颗粒增强的铝基复合材料,合成的复合材料硬度比ZL102提高37.3%.     

自生颗粒增强铝基复合材料的组织与性能

本文采用原位反应工艺,通过在Al熔体中加入TiO2,在一定温度下产生化学反应生成Al3Ti颗粒,用铸造法制备Al/Al3Ti复合材料.自生的Al3Ti颗粒尺寸细小,分布均匀.当TiO2/Al质量比为20%～30%、反应温度为920℃时,所制备的复合材料的抗拉强度比纯Al基体提高77.5%,硬度提高132%,而延伸率较纯铝略有下降.     

原位合成TiB_2颗粒增韧SiC的显微组织与断裂韧性

在前期对原位生成TiB2增韧SiC制备工艺研究的基础上,研究了TiB2/SiC复合陶瓷的显微组织与力学性能.研究发现:在φ(TiB2)介于5%~20%时,原位生成的TiB2相在SiC基体中的分布都比较均匀;当φ(TiB2)为5%和20%时,TiB2颗粒等面积圆直径平均值分别为2.6和3.9μm;另外,TiB2颗粒能起到明显细化SiC晶粒的作用.随着φ(TiB2)的增加,TiB2/SiC复合材料的相对密度、维氏硬度和断裂韧性均增大.当φ(TiB2)为20%时,复合材料相对密度、维氏硬度和断裂韧性分别为94.8%,29.1 GPa和5.9 MPa.m1/2.经优化工艺制备的TiB2/SiC复合陶瓷...     

微合金化对原位复合材料组织与性能的影响

利用熔体原位反应法制备了(Al2O3 Al3Zr)p/A356复合材料.研究了添加质量分数均为0.2%的Mn和Cr微合金元素对所制备的复合材料微观组织和室温力学性能的影响.SEM分析结果表明:添加微合金元素改善了(Al2O3 Al3Zr)p/A356复合材料的微观组织,原位Al3Zr颗粒和初生α相得到了有效细化,尺寸大部分为2～3 μm,增强颗粒均匀分布在A356基体中,颗粒呈球形或椭球形.室温拉伸试验结果表明,添加微合金元素对复合材料的力学性能有一定程度的改善,其抗拉强度σb,屈服强度σs和延伸率δ较添加前分别提高了13.9%,16.9%和10.6%,达到326.1MPa,252.2 MPa和5.2%.SEM拉伸断口形貌分析表明,其断裂属于塑性断裂.     

ZrB2 SiC/Zr Al C复合材料的制备与性能

采用放电等离子烧结技术(SPS)制备原位自生纳米层状Zr Al C相改性ZrB2 SiC复合材料,研究不同烧结温度对纳米层状Zr Al C相改性ZrB2 SiC复合材料的物相组成、微观结构和力学性能的影响,并探讨材料的强韧化机制.结果表明:在1 500,1 600,1 700 ℃烧结温度下,均原位合成了纳米层状Zr Al C相,厚度在几十纳米到几百纳米之间;烧结温度从1 500 ℃升高到1 700 ℃时,复合材料的断裂韧性由（4.51±0.04） MPa·m1/2提高至（5.04±0.02） MPa·m1/2,维氏硬度由（7.3±1.1） GPa提高至（14.2±1.1） GPa,断裂韧性和维氏硬度分别提高约12%和95%;随着烧结温度的升高,试样的致密度提高，气孔减少，晶粒间结合更紧密,断裂韧性和维氏硬度都逐渐增大.     

原位合成TiB/Ti复合材料的微观结构及力学性能

利用钛与硼之间的自蔓延高温合成反应经普通的熔铸工艺原位合成制备了TiB增强的钛基复合材料.通过XRD、SEM、TEM和HREM等分析方法测试了合成材料的物相及微观结构.结果表明原位合成的增强体为TiB,合金化元素铝的加入并不导致新相形成,增强体均匀地分布在基体合金上.由于TiB的B27结构导致TiB易于沿[010]方向生长而长成短纤维状.增强体与基体合金界面非常洁净,没有任何界面反应.由于原位合成增强体的加入,复合材料的力学性能与基体合金比较有了明显的提高.     

应用于电火花加工电极材料的TiB2/Cu复合材料

实验研究了作为电火花加工电极材料的两种含量的TiB2/Cu复合材料.以加工速度、电极损耗率为工艺指标,分别研究了加工电流、脉冲宽度在电火花加工过程中的影响,并采用PHILIPS XL-30环境扫描电镜(Environmental Scanning Electron Microscope,简称ESEM)及能谱(Energy Dispersive X-ray,简称 EDX)分析TiB2/Cu复合材料作为电火花加工电极材料的腐蚀机理.实验结果表明,将体积分数为5%的TiB2/Cu复合材料作为电火花加工电极材料与其他的铜基复合材料具有同样的规律.     

Processing and characterization of the microstructure and mechanical properties of Al6061–TiB2 composite

In the present research, aluminum metal matrix composites were processed by the stir casting technique. The effects of TiB2 rein-forcement particles, severe plastic deformation through accumulative roll bonding (ARB), and aging treatment on the microstructural charac-teristics and mechanical properties were also evaluated. Uniaxial tensile tests and microhardness measurements were conducted, and the micro-structural characteristics were investigated. Notably, the important problems associated with cast samples, including nonuniformity of the rein-forcement particles and high porosity content, were solved through the ARB process. At the initial stage, particle-free zones, as well as particle clusters, were observed on the microstructure of the composite. However, after the ARB process, fracturing phenomena occurred in brittle ceramic particles, followed by breaking down of the fragments into fine particles as the number of rolling cycles increased. Subsequently, com-posites with a uniform distribution of particles were produced. Moreover, the tensile strength and microhardness of the ARB-processed com-posites increased with the increase in the reinforcement mass fraction. However, their ductility exhibited a different trend. With post-deforma-tion aging treatment (T6), the mechanical properties of composites were improved because of the formation of fine Mg2Si precipitates.     

熔体直接反应法制备Al/TiB2复合材料铸态组织和性能

对AI-TiO2-KBF4反应体系,采用熔体直接反应法制备了AI/TiB2复合材料。研究表明：采用合适的熔剂,可降低反应所需温度;细小的TiB2颗粒均匀地分布在铝基体上,当TiO2加入量为10％时,AI／TiB2复合材料的抗拉强度较基体提高了84．5％,而伸长率为12．7％;重熔除气对复合材料组织分布影响不大,重熔除气后复合材料的抗拉强度较基体提高了98．9％,伸长率为10．8％。     

钨合金力学行为的计算机数值模拟─—宏观力学性能

在微观力学行为分析的基础上，对90W合金宏观力学性能及其与微观结构因素（粘结相力学参数）之间的关系进行了计算机数值模拟研究．结果表明：钨合金性能与粘结相力学参数密切相关．随着粘结相弹性模量增加，合金的抗拉强度增加，但延伸率降低．当粘结相屈服强度800MPa时，合金抗拉强度随粘结相屈服强度增加而增大，在粘结相屈服度为800MPa时达到最大值．随粘结相抗拉强度增加，合金抗拉强度和延伸率均呈近似线性规律增加．合金延伸率对粘结相应变硬化模量极为敏感．     

2519铝合金的低温拉伸力学性能

利用拉伸测试、扫描电镜与透射电镜等手段，研究室温和液氮温度下2519铝合金板材的拉伸力学性能。研究结果表明：当变形温度由293K降至77K时，合金纵向抗拉强度由493．64MPa升至607．35MPa，提高了23．1％，屈服强度由454．83MPa上升到516．53MPa，提高了13．7％；合金低温横向抗拉强度与屈服强度分别提高了23．6％和20．0％。低温变形时合金横向、纵向伸长率均稍有提高。这是由于在低温变形过程中平面滑移受抑制，加工硬化指数增加，变形均匀性增强，导致材料的强度增加，塑性提高。     

Fabrication of homogeneously dispersed graphene/Al composites by solution mixing and powder metallurgy

Graphene-reinforced aluminum (Al) matrix composites were successfully prepared via solution mixing and powder metallurgy in this study. The mechanical properties of the composites were studied using microhardness and tensile tests. Compared to the pure Al alloy, the graphene/Al composites showed increased strength and hardness. A tensile strength of 255 MPa was achieved for the graphene/Al composite with only 0.3wt% graphene, which has a 25% increase over the tensile strength of the pure Al matrix. Raman spectroscopy, Fourier transform infrared spectroscopy, scanning electron microscopy, and transmission electron microscopy were used to investigate the morphologies, chemical compositions, and microstructures of the graphene and the graphene/Al composites. On the basis of fractographic evidence, a relevant fracture mechanism is proposed.     

Effect of graphite powder as a forming filler on the mechanical properties of SiCp/Al composites by pressure infiltration

(38vol% SiCp + 2vol% Al₂O_3f)/2024 Al composites were fabricated by pressure infiltration. Graphite powder was introduced as a forming filler in preform preparation, and the effects of the powder size on the microstructures and mechanical properties of the final composites were investigated. The results showed that the composite with 15 μm graphite powder as a forming filler had the maximum tensile strength of 506 MPa, maximum yield strength of 489 MPa, and maximum elongation of 1.2%, which decreased to 490 MPa, 430 MPa, and 0.4%, respectively, on increasing the graphite powder size from 15 to 60 μm. The composite with 60 μm graphite powder showed the highest elastic modulus, and the value decreased from 129 to 113 GPa on decreasing the graphite powder size from 60 to 15 μm. The differences between these properties are related to the different microstructures of the corresponding composites, which determine their failure modes.     

烧结工艺对TiB2增强铜基复合材料性能的影响

利用机械合金化Ｃｕ（Ｔｉ,Ｂ）过饱和固溶体在真空加压烧结炉中进行加压烧结,制备了ＴｉＢ２增强铜基复合材料,对ＴｉＢ２增强铜基复合材料烧结工艺和性能的研究结果表明：ＴｉＢ２增强铜基复合材料的最佳烧结工艺是烧结温度为８９０℃,烧结压强为５０ＭＰａ,保温和加压时间为２．５ｈ,ＴｉＢ２增强铜基复合材料的硬度随ＴｉＢ２含量的增加有所提高,导电率随ＴｉＢ２含量的增加有所下降,软化温度基本保持在９００℃左右。