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《功能材料》2015,(19)
采用悬浮熔炼-水冷铜模吸铸法制备了(Ti0.5Ni0.5-xZrx)80Cu20(x=0,0.02,0.04,0.06和0.08)。通过对Zr的添加量的控制制备具有组织连续梯度的非晶复合材料,研究其组织和力学行为及微量Zr的添加对此非晶复合材料的组织和力学性能的影响。结果表明,凝固过程的温度梯度决定了复合材料的组织梯度,由表及里,主要为非晶相、马氏体相和奥氏体树枝晶相。铸态非晶基体上析出了B2-Ti(Ni,Cu)过冷奥氏体相和B19’-Ti(Ni,Cu)热诱发马氏体相,加载断裂后应力诱发马氏体相变,马氏体衍射峰比铸态增强且马氏体择优取向。随着Zr的不断添加,此系列非晶合金非晶形成能力先提高后降低,奥氏体含量不断下降,相变诱发塑性减弱,从而塑性逐级递减,强度先升高后降低。 相似文献
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F. J. Balta Calleja L. Giri T. Asano T. Mieno A. Sakurai M. Ohnuma C. Sawatari 《Journal of Materials Science》1996,31(19):5153-5157
The microhardness of films of fullerene-polyethylene composites prepared by gelation from semidilute solution, using ultrahigh molecular weight polyethylene (PE) (6×106), has been determined. The composite materials were characterized by optical microscopy and X-ray diffraction techniques. The microhardness of the films is shown to increase notably with the concentration of fullerene particles within the films. In addition, a substantial hardening of the composites is obtained after annealing the materials at high temperatures (T
a=130 °C) and long annealing times (t
a=105s). The hardening of the composites with annealing temperature has been identified with the thickening of the PE crystalline lamellae. Comparison of X-ray scattering data and the microhardness values upon annealing leads to the conclusion of phase separation of C60 molecules from the polyethylene crystals within the material. The temperature dependence is discussed in terms of the independent contribution of the PE matrix of the C60 aggregates to the hardness value. 相似文献
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Asit Kumar Khanra Hwa Chul Jung Seung Hoon Yu Kug Sun Hong Kwang Seon Shin 《Bulletin of Materials Science》2010,33(1):43-47
In the present study, it has been attempted to develop biodegradable Mg-HAP (magnesium-hydroxyapatite) composite materials
for bone replacement. At first the HAP powders were prepared by chemical synthesis process and synthesized powders were characterized
by X-ray diffraction (XRD) and scanning electron microscope (SEM). Synthesized powders contain HAP as a major phase with tricalcium
phosphate (β-TCP) as a minor phase. The Mg-HAP composites were prepared by adding different amounts of HAP powders to Mg melts and finally
the billets were extruded. The microstructure of Mg-HAP composite was examined by optical microscope (OM). The presence of
HAP in Mg matrix results in decrease of grain size of Mg-HAP composites. The theoretical and experimental hardness of the
composites are compared with the addition of HAP. The tensile strength of composites is found to decrease with the addition
of HAP, whereas compressive strength increases with HAP. 相似文献
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将乙烯醋酸乙烯酯共聚物(EVA)、 丙烯酸酯弹性体(AR)和云母(Mica)熔融共混制备了一系列复合材料。动态力学分析发现, EVA与AR共混后, tanδ在5℃附近出现了新峰; 在EVA-AR(80/20)中加入聚合级空间受阻酚MPDI(4-甲基-苯酚与二环戊二烯和异丁烯的反应产物), tanδ峰值逐渐增大, 且峰位置逐渐向高温方向偏移。云母的加入使EVA-AR-MPDI共混物的tanδ峰位置明显向高温方向偏移, 而且峰宽拓宽明显。随着云母含量的增加, 高温区tanδ数值逐步变大, 损耗模量E″大幅度提高, 当云母含量为58.8wt%时E″峰值由未加云母时的79MPa增加至280MPa, 并且E″峰位置向高温偏移。氢键红外光谱和扫描电镜分析结果表明, 复合材料阻尼性能有所提高。 相似文献
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The dynamic mechanical analysis (DMA) method was utilized to investigate the dynamic mechanical properties of the carbon-phenolic composite, and of carbon-carbon (C/C) composites carbonized at 1000°C, and graphitized at 2200°C. The measurements were performed in the temperature range 50–450°C. Results show that the carbon-phenolic composite has the highest storage modulus, while the carbonized C/C composites possess higher storage modulus than the graphitized C/C composite. The storage moduli of carbonized and graphitized C/C composite do not change significantly in the test temperature range. The tan , loss factor, of carbonized C/C composites increases 59.5% during the tests from 50 to 450°C, and that of the graphitized C/C decreases 9.74% in the same temperature range; graphitized C/C shows the highest tan at 50 °C. The carbon-phenolic composite shows a damping peak at 250 °C, which is probably due to the transition from glassy state to rubbery state of the phenolic matrix. The higher tan of the graphitized C/C composite may be due to matrix graphitization, fibre-matrix debonding and crack formation, which were observed on the micrographs. 相似文献
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Textile composites manufactured using Resin Transfer Modeling (RTM) can offer advantages in some automotive applications including reduction in weight, while being relatively simpler to fabricate than standard laminated composites used for aerospace applications. However, one of the challenges that arise with these textile composite materials is that the mechanical properties are inherently dependent on the local and final (in-situ) architecture of the textile itself as a result of the molding and curing processes. While this provides additional latitude in the composite design process it also necessitates the development of analytical models that can estimate the mechanical properties of a textile composite based on the textile architecture and the properties of the manufactured component.In this paper, an analytical model is developed and its estimations are compared against experimental in-plane engineering properties for composites with various textile architectures. Results from the model are also compared against finite element (FE) based computational results. The microstructures of the 2D triaxially braided composite (2DTBC) studied were extensively characterized. The microstructure properties thus measured were used in the analytical model to estimate the mechanical properties. Uniaxial tension and V-notched rail shear tests were conducted on 2DTBC with different textile architectures. Good agreement between the analytical, computational, and experimental results were observed and are reported here. Furthermore, computational estimations of matrix mechanical properties are limited to the linear elastic range of a representative material volume (unit cell) and coupon data. Full mechanical response of larger 2DTBC structures, albeit of prime interest, is beyond the scope of this work and could be the focus of follow up studies. 相似文献
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Masaki Kimoto 《Journal of Materials Science》1990,25(7):3327-3332
The viscoelastic behaviour of glass fibre (GF)-epoxy composites was studied by flexural tests and dynamic mechanical measurements. In relation, the influence of surface treatment of GF on viscoelastic behaviour was also examined. Using the results of flexural tests under a variety of constant temperature and strain rate, master curves of flexural strength () and flexural strain () were obtained for matrix epoxy and GF composites. The magnitudes of the master curves were different between matrix epoxy and GF composites. The fracture mode was influenced by temperature, strain rate, and G F surface treatment. The magnitude of storage modulus and effectiveness of adhesion at the GF-matrix interface were also influenced by GF surface treatment. Relationship between the results of flexural strain and loss modulus were considered for GF composites. 相似文献
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Zirconium carbide containing up to 40 wt% yttria-stabilized zirconia was sintered at 1800 to 2200° C in argon and carbon monoxide atmospheres in a graphite tube furnace. Well-dispersed fine powders containing 20 wt% ZrO2 or more, when formed into compacts with green densities of 55% or above, could be sintered to theoretical density in 1 h at 2000° C. The resulting microstructure consisted of a dispersed ZrO2 phase in a continuous zirconium oxi-carbide matrix. The fracture toughness and four-point bend strength were a maximum at 40 wt% ZrO2 and were 5.8 MPa m1/2 and 320 MPa, respectively. The fracture surface was irregular and primarily intergranular. 相似文献
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Maurizio Avella Ezio Martuscelli Claudio Sellitti Enea Garagnani 《Journal of Materials Science》1987,22(9):3185-3193
The influence of glass fibres on the primary nucleation process, isothermal radial growth rate of spherulites and overall kinetic rate constant of isotactic polypropylene (iPP) has been examined. The polypropylene was also modified by means of acrylic acid (iPP*) in order to improve the adhesion between the matrix and the fibres, and the relative properties were compared with those concerning the composites having as matrix plain MR Moreover the mechanical properties of injection-moulded composites containing iPP and iPP* have been studied. These properties improved on increasing the fibre content. It was found that for the same glass-fibre content better values of the elongation at break and creep are observed in the case of reinforced polypropylenes having as matrix acrylic acid modified polypropylene. 相似文献
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Niobium aluminide-based composites reinforced with in situ and externally added Al2O3 and TiC particulates were fabricated by hot-pressed sintering at 1400 °C. In particular, Nb2Al–Al2O3–TiC in situ composites were successfully obtained from the raw powder mixtures of Nb60Al40 (in at.%)–TiO220C8 (in wt.%) by means of this process. The influences of ceramic particulates on the microstructures, flexural strength and fracture toughness were examined. The experimental results indicate that the presence of ceramic particulates yielded a remarkable improvement in both the strength and fracture toughness in comparison with previous results for monolithic niobium aluminide compounds. 相似文献
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Hot-pressed SiC-TiC composite ceramics with 0–100 wt% TiC have been investigated to determine the effect of composition (amount of TiC) on the elastic modulus, hardness, flexural strength and fracture toughness,K
IC. The composites exhibited superior mechanical properties compared to monolithic SiC and TiC, especially in fracture toughness,K
IC, value for 30–50 wt% TiC composite. The maximum values ofK
IC and room-temperature flexural strength were 6 MPa m1/2 for a 50 wt % TiC and 750 MPa for a 30 wt% TiC composite, respectively. The observed toughening could be attributed to the deflection of cracks due to dispersion of the different particles. Although no third phases were detected by both TEM and XRD studies, an EDAX study and resistivity measurements indicated some possibility of solid solutions being present. The composites containing more than 30 wt% TiC, exhibited resistivity lower than 10–3 cm which is favourable for electro-discharge machining of ceramics. 相似文献
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K. Takatori 《Journal of Materials Science》1991,26(16):4484-4490
Compositions of Al2O3, Si3N4 and AlN were sintered to produce six different alumina-sialon composites. The composites reached the highest density at 1700 °C in a nitrogen atmosphere. Sialon acted as a binder, promoting the densification and suppressing the grain growth of alumina. The composites had a bending strength of 450 MPa at room temperature and maintained high strength over 300 MPa at 1400 °C. The composite with 30 wt % sialon had the maximum fracture toughness of 4.3 MPa·m1/2 and exhibited good oxidation resistance even at 1400 °C. Mullite was formed in the oxidation layer and little degradation in strength was observed after oxidation. 相似文献
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Fabrication and mechanical properties of fine-tungsten-dispersed alumina-based composites 总被引:5,自引:0,他引:5
The mechanical properties and microstructure of fine-tungsten-dispersed alumina-based composites, which were fabricated by
hot pressing a mixture of fine α-Al2O3 and W powders, have been investigated. Small W particles of approximately 140 nm average
size were located within the Al2O3 matrix grains. The mechanical properties were influenced by the metal content and sintering
conditions. When the appropriate W content and sintering condition were selected (typically 5–10 vol% W and sintered at 1400°C),
the fracture strength was enhanced compared with that of monolithic Al2O3. The metal content dependence of Young's modulus
and the Vickers hardness did not obey the rule of mixtures. This may be attributed to the presence of localized residual stress
caused by the incorporation of fine W dispersion into Al2O3. On the other hand, high-temperature (1600°C) sintering caused
degradation in the properties of the composites due to the grain growth and chemical reaction of W dispersion, which was revealed
by X-ray photoelectron spectroscopy analysis. The relations between fabrication condition and mechanical properties are discussed.
This revised version was published online in November 2006 with corrections to the Cover Date. 相似文献
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Changes to the tensile and flexure properties of marine-grade glass-reinforced polyester, vinyl ester and resole phenolic composites after exposure to radiant heat are investigated. The properties were determined at room temperature after the composites had been exposed to heat fluxes of 25–100 kW/m2 for 325 s or to a heat flux of 50 kW/m2 for increasing times up to 1800 s. The stiffness and failure load of all three composites decreased rapidly with increasing heat flux or time due mainly to the thermal degradation of the resin matrix. The post-fire tension and flexure properties of the resole phenolic composite were similar to the properties of the other composites, despite its superior fire resistance. Models are presented for determining the post-fire mechanical properties of fire-damaged composites, and are used to estimate the reductions in failure load of composite ship materials caused by fire. 相似文献
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《Composites》1993,24(5):423-432
The mechanical properties of composites prepared from two types of non-crimped fabric (NCF), namely biaxial, ±45° and quadriaxial with a 0°, ±45°, 90°, −45° ply sequence, are examined as a function of fabric weight and compared with those of alternative composite forms. In general, the properties of NCF laminates decrease slightly as the areal weight of the fabric increases. Laminates produced from biaxial fabrics exhibit superior properties for a given volume fraction of reinforcement than do laminates produced using woven rovings or continuous fibre prepregs, while quadriaxial NCF laminates have equivalent properties to woven roving laminates at certain orientations but, unlike woven roving laminates, retain their properties when rotated through 45°. Biaxial NCFS loaded at 45° to the fibre and quadriaxial fabrics produce composites with superior properties to those predicted using finite element and laminate analysis for idealized laminates based on the same materials. 相似文献
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Lee AJ Ling RS Gheduzzi S Simon JP Renfro RJ 《Journal of materials science. Materials in medicine》2002,13(8):723-733
The aim of this paper is to report a series of experiments investigating the factors that influence the viscoelastic properties of acrylic bone cement. The effects of the brand of cement, the length of time since mixing, temperature, the hydration of the cement, and the influence of fat and or blood in the environment on the creep and stress relaxation behavior of the cement have been studied in laboratory-prepared specimens in tension, compression and four point bending. Although there are significant differences in the viscoelastic behavior of some of the different brands of polymethylmethacrylate based cements, these differences are small by comparison with the major effects that can be exerted by the length of time since mixing and some environmental factors. These effects have important practical consequences, especially with regard to the ability of bench top and theoretical studies to predict reliably the mechanical and viscoelastic behavior of acrylic cement in vivo. 相似文献
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Magnesium (Mg) composite reinforced with carbon nanotubes (CNTs) having superior mechanical properties was fabricated using both pure Mg and AZ61 Mg alloy matrix in this study. The composites were produced via powder metallurgy route containing wet process using isopropyl alcohol (IPA) based zwitterionic surfactant solution with unbundled CNTs. The produced composites were evaluated with tensile test and Vickers hardness test and analyzed by X-ray diffraction (XRD) and field-emission scanning electron microscopy (FE-SEM) equipped with energy dispersive spectroscopy (EDS) and electron back scattered diffraction (EBSD). As a result, only with AZ61 Mg alloy matrix, tensile strength of the composite was improved. In situ formed Al2MgC2 compounds at the interface between Mg matrix and CNTs effectively reinforced the interfacial bonding and enabled tensile loading transfer from the Mg matrix to nanotubes. Furthermore, it was clarified that the microstructures and grain orientations of the composite matrix were not significantly influenced by CNT addition. 相似文献
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金属铜木材复合材料的制备及其力学性能研究 总被引:2,自引:0,他引:2
以速生林泡桐木材为基体,次亚磷酸钠为还原剂,乙二酸四乙酸二钠(EDTA)为络合剂,利用水热法在木材基质内将醋酸铜原位还原得到金属铜木材复合材料。通过X-射线衍射仪(XRD)、光学显微镜和扫描电子显微镜(SEM)对木材复合材料的结构形貌进行表征,使用万能力学实验机测试改性木材的力学性能。XRD结果显示在2θ为43.22°和50.36°出现了金属铜的特征衍射峰;光学显微和SEM结果显示金属铜均匀分布在木纤维细胞壁上;力学性能测试结果表明:改性木材的弹性模量、抗压强度和比例极限较素材增强明显,最大较素材分别增加了41.60%、51.30%和42.71%。 相似文献