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1.
采用挤压铸造法制备了Al2O3f/Al-5Cu复合材料,研究了其凝固组织及其溶质在纤维附近的分布。结果表明:纤维与基体间润湿良好,生成了致密的界面层;在凝固过程中,αAl相在短纤维间隙中形核并向纤维表面生长;纤维表面Cu和h元素的浓度增大,纤维间隙中的Cu元素的浓度减小。La的加入改变了凝固过程中的溶质传质参数,根据Clyne-Kurz公式的计算和统计物理的分析,将会生成更多的共晶组织。 相似文献
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连续SiC纤维增强钛基复合材料(SiCf/Ti)具有良好的综合性能,但其横向性能低于钛合金基体。为了准确地预测SiCf/Ti复合材料的横向强度,北京航空制造工程研究所赵冰等人提出一种基于界面脱粘强度的计算模型。采用SiCf/Ti复合材料十字拉伸试件来测试复合材料的纤维/基体界面脱粘强度,并分析了热处理时间对界面脱粘强度影响规律,以及不同纤维之间界面脱粘强度的差别。 相似文献
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提出了一种可以制备冶金结合界面双金属复合板带的水平连铸复合成形新工艺,其具有短流程、高效的特点。采用该工艺制备了截面尺寸为70 mm×24 mm(宽度×厚度)的铜铝复合板,获得了可行的制备参数,研究了所制备板坯的组织形貌和性能。结果表明,铜铝复合板制备成形过程中,会形成由金属间化合物和共晶相组成的复合界面层。铝液和铜板表面接触,发生固液转变形成(II)层:θ相。随着铜原子不断的向铝液中扩散,当铜原子含量达到一定程度,θ相发生固相转变形成(I)层:γ相。达到共晶温度时,发生共晶转变形成(III)层:α+θ共晶组织。其中I层和II层均为铜铝金属间化合物,是裂纹产生和扩展的主要区域,因此界面层厚度是决定结合强度的重要因素。通过调整工艺参数可以优化凝固过程中铜铝复合板内的温度场分布,进而控制复合界面层的形成过程,因此工艺参数之间的合理匹配是改善复合层组织结构和增大板坯结合强度的关键。 相似文献
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为了研究铜元素含量变化对复合材料界面反应、微观组织结构和机械性能的影响,利用挤压铸造法制备了体积分数均为40%的Al2O3纤维增强纯铝和Al—Cu合金(1%,3%和5%)复合材料。采用X射线、TEM、SEM和拉伸实验手段,观察和测试了4种复合材料的微观组织和机械性能。结果表明,Al2O3纤维表面含有非晶SiO2成分,在高应力下易于开裂。铜元素的加入对材料的析出产生和机械性能有重要影响。铜元素引入后在复合材料中纤维表面处偏聚和富集,促进了界面θ相析出,并随基体中Cu含量提高而增加。当铜含量增加到5%后,基体内部也出现明显的析出相。拉伸实验结果表明随着Cu含量的增加复合材料的抗拉强度增高,Al2O3f/Al-Cu与Al2O3f/纯Al相比,抗拉强度分别增加了102%,146%和171%。SEM断口观察表明:基体合金的断口基本上都呈宏观脆性断口,具有低的展延性和撕裂纹理;大量的纤维从复合材料基体中拔出,一些纤维被拉断,这些特点与界面结合物和多晶的Al2O3纤维结构密切相关。 相似文献
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通过箔-纤维-箔法制备了SiC纤维增强TB8复合材料,采用光学电子显微镜(OM)、扫描电镜(SEM)和电子探针(EPMA)对复合材料的微观组织进行表征与分析,研究了真空热压复合时压力、温度和时间工艺参数对SiC纤维增强TB8复合材料微观组织的影响规律。结果表明:压力对复合材料基体与基体以及纤维与基体的结合有着显著影响,而温度对纤维与基体界面反应层影响较大。通过热压工艺的优化,可以有效控制界面反应层厚度,获得组织优良的SiC f/TB8复合材料。 相似文献
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《稀有金属》2015,(7)
利用TC4,Al廉价材料,通过磁控溅射物理气相沉积技术制备SiC先驱丝,利用热等静压工艺,在温度1423 K,压力170 MPa条件下进行复合,反应时间为1 h,通过原位反应生成Ti3Al基体,从而制备SiC纤维增强Ti3Al基复合材料。通过扫描电镜(SEM)和能谱分析(EDS)观察SiC纤维增强Ti3Al基复合材料基体与界面的微观组织形貌及界面元素分布,利用透射电镜(TEM)分析复合材料基体的物相结构,并对SiC纤维增强Ti3Al基复合材料的界面反应进行动力学分析。结果表明,利用TC4,Al制备的SiC先驱丝,通过原位反应可生成Ti3Al基体,属于六方晶系,组织为等轴晶,晶粒尺寸约为1μm。通过磁控溅射和热等静压工艺制备SiC纤维增强Ti3Al基复合材料,可缩短工艺流程,节约成本。根据SiC纤维增强Ti3Al基复合材料界面反应层生长动力学分析,得到界面反应层生长动力学方程:δ=2.73×10-6exp(-257.09×103/RT)t1/2,可准确预测连续碳化硅纤维增强Ti3Al基复合材料在制备和使用过程中界面反应层的生长规律,为其应用提供理论依据。 相似文献
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Yoshinori Nishida Norihisa Izawa Yukio Kuramasu 《Metallurgical and Materials Transactions A》1999,30(13):839-844
Separation of matrix metals in composites was tried on alumina short fiber-reinforced aluminum and 6061 alloy composites and
SiC whisker-reinforced 6061 alloy composite for recycling. It is possible to separate molten matrix metals from fibers in
the composites using fluxes that are used for melt treatment to remove inclusions. About 50 vol pct of the matrix metals was
separated from the alumina short fiber-reinforced composites. The separation ratio of the matrix from the SiC swisker-reinforced
6061 alloy composite was low and about 20 vol pct. The separation mechanism was discussed thermodynamically using interface
free energies. Since the flux/fiber interface energy is smaller than the aluminum/fiber interface energy, the replacement
of aluminum with fluxes in composites takes place easily. Gases released by the decomposition of fluxes act an important role
in pushing out the molten matrix metal from the composite. The role was confirmed by the great amount cavity formed in the
composite after the matrix metal flowed out. 相似文献
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Yoshinori Nishida Norihisa Izawa Yukio Kuramasu 《Metallurgical and Materials Transactions A》1999,30(3):839-844
Separation of matrix metals in composites was tried on alumina short fiber-reinforced aluminum and 6061 alloy composites and
SiC whisker-reinforced 6061 alloy composite for recycling. It is possible to separate molten matrix metals from fibers in
the composites using fluxes that are used for melt treatment to remove inclusions. About 50 vol pct of the matrix metals was
separated from the alumina short fiber-reinforced composites. The separation ratio of the matrix from the SiC whisker-reinforced
6061 alloy composite was low and about 20 vol pct. The separation mechanism was discussed thermodynamically using interface
free energies. Since the flux/fiber interface energy is smaller than the aluminum/fiber interface energy, the replacement
of aluminum with fluxes in composites takes place easily. Gases released by the decomposition of fluxes act an important role
in pushing out the molten matrix metal from the composite. The role was confirmed by the great amount cavity formed in the
composite after the matrix metal flowed out. 相似文献
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A. Muthuchamy G. D. Janaki Ram V. Subramanya Sarma 《Transactions of the Indian Institute of Metals》2018,71(4):941-949
In the current research work, spark plasma consolidated beta-titanium alloy Ti–15V–3Cr–3Al–3Sn composites reinforced with SiC fibers (Sigma SM1240) were subjected to high temperatures (1173, 1223 and 1273 K) for different time periods (2.7, 11, 25 and 44 h) to investigate the kinetics of the chemical reactions at the fiber/matrix interface. Through microstructural studies and room temperature tensile tests, we have attempted to study the effect of the formed brittle reaction zone on the final mechanical properties of the composite. We have observed that, prior to the SiC fiber, the protective carbon coating reacts with the matrix and results in the formation of a reaction zone (predominantly TiC) at the fiber/matrix interface. The reaction zone propagates into the matrix with increase in time at the expense of the carbon coating, and finally ends with the onset of titanium silicide reaction. The reaction kinetics at the fiber/matrix interface was predominantly controlled by diffusion of carbon through the reaction zone and the activation energy for the same was calculated to be 149 kJ/mol. It was clear from the tensile test results that the mechanical properties of the composites do not earnestly decrease until the commencement of titanium silicide reaction. 相似文献
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Unlike many eutectic composites, the Ni-W eutectic exhibits extensive ductility by slip. Furthermore, its properties may be greatly varied by proper heat treatments. Here results of studies of deformation in both monotonic and fatigue loading are reported. During monotonie deformation the fiber /matrix interface acts as a source of dislocations at low strains and an obstacle to matrix slip at higher strains. Deforming the quenched-plus-aged eutectic causes planar matrix slip, with the result that matrix slip bands create stress concentrations in the fibers at low strains. The aged eutectic reaches generally higher stress levels for comparable strains than does the as-quenched eutectic, and the failure strains decrease with increasing aging times. For the composites tested in fatigue, the aged eutectic has better high-stress fatigue resistance than the as-quenched material, but for low-stress, high-cycle fatigue their cycles to failure are nearly the same. However, both crack initiation and crack propagation are different in the two conditions, so the coincidence in high-cycle fatigue is probably fortuitous. The effect of matrix strength on composite performance is not simple, since changes in strength may be accompanied by alterations in slip modes and failure processes. 相似文献
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Unlike many eutectic composites, the Ni-W eutectic exhibits extensive ductility by slip. Furthermore, its properties may be
greatly varied by proper heat treatments. Here results of studies of deformation in both monotonic and fatigue loading are
reported. During monotonie deformation the fiber /matrix interface acts as a source of dislocations at low strains and an
obstacle to matrix slip at higher strains. Deforming the quenched-plus-aged eutectic causes planar matrix slip, with the result
that matrix slip bands create stress concentrations in the fibers at low strains. The aged eutectic reaches generally higher
stress levels for comparable strains than does the as-quenched eutectic, and the failure strains decrease with increasing
aging times. For the composites tested in fatigue, the aged eutectic has better high-stress fatigue resistance than the as-quenched
material, but for low-stress, high-cycle fatigue their cycles to failure are nearly the same. However, both crack initiation
and crack propagation are different in the two conditions, so the coincidence in high-cycle fatigue is probably fortuitous.
The effect of matrix strength on composite performance is not simple, since changes in strength may be accompanied by alterations
in slip modes and failure processes. 相似文献
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Coarsening and microstructural changes, which occur on cooling from the eutectic temperature, were experimentally studied
in Al-Al3Ni eutectic fiber composites solidified at rates of 0.8, 5.0 and 32.5 cm per h. At the two higher growth rates, changes in
fiber density on the order of 10 pct were observed between the solid-liquid interface and positions 2.0 cm from the interface.
At the low growth rate the surface roughness of the as-grown fiber was noticeably decreased during cooling from the eutectic
temperature. Theoretical expressions relating the change in average fiber radius or fiber density as a function of position
were developed in terms of the solidification conditions, growth rate and temperature gradient, as well as the usual kinetic
and thermodynamic factors influencing coarsening. The model was combined with independently obtained isothermal coarsening
data to compare the experimentally observed extent of coarsening with that predicted. The pre-dictions of the model agreed
qualitatively with the data on the effect of growth rate on coarsening, but the absolute extent of coarsening was greater
than that predicted from the isothermal studies. 相似文献
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Zn Alalloyisoneofalloymaterialswide lyusedinindustry .Zn 5Aleutecticalloyisnotonlyextensivelyusedasdie castingalloy ,hotplatingandsprayingalloy ,butobtainsrecognitioninsuperplasticshapingandsuper plastictheoreticalresearchesowingtoitsex traordinarysuperpla… 相似文献
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A comprehensive investigation is made of the parameters affecting the extent of interface reactions during squeeze casting
of composites consisting of a matrix of either pure Al or alloy AS13 reinforced with fibers of INCONEL 601. The process parameters
are the preform thickness and temperature, the fiber volume fraction, the temperature and mass of the liquid metal, and the
temperature of the die. Adjustment of these process parameters made possible the full control of reactions. It is found that
reactions proceed mainly in the solid state after decomposition of the oxide barrier layer covering the fibers. A simple kinetic
model is developed that enlightens the role of this barrier layer. No trace of reaction could be detected in composites processed
using preoxidized preforms. Alloying Al with Si also induces a drastic reduction of reactivity. The high ductility of the
composites attests to the processing quality. An original procedure is proposed for measuring the activation energy for initiation
of reactions by differential thermal analysis. 相似文献