共查询到20条相似文献,搜索用时 15 毫秒
1.
对SiC2/Al2O3陶瓷的低粘度、高固相体积分数浓悬浮体的制备以及凝胶注模成型后坯体的性能和显微结构进行了研究,着重分析了长径比不同的2种SiC晶须及其添加量对坯体性能的影响.结果表明,坯体的相对密度、抗弯强度与SiC晶须的长径比和添加量有关,浆料的粘度随着晶须长径比和添加量的增大而增加.坯体的抗弯强度随着晶须添加量的增加呈现一种先上升后下降的趋势.凝胶注模成型后坯体结构均匀、致密,相对密度为60%,抗弯曲强度达38.5 MPa.通过显微结构观察,裂纹偏转、晶须拔出和晶须桥连是晶须增强的主要机制. 相似文献
2.
1 INTRODUCTIONTheresidualthermalstresscausedbythemis matchofcoefficientsofthermalexpansion (CTE)be tweenreinforcementandmatrixalloyandhighdensi tydislocationsinthevicinityoftheinterfacesresultedfromtherelaxationofresidualstressoncoolinghavegreatinfluenc… 相似文献
3.
对机械合金化制备的Al_4C_3、Al_2O_3弥散质点和SiC颗粒复合强化Al基复合材料进行了拉伸试验和断口分析,并测定了弹性模量和热膨胀系数.研究表明,在SiC_p/Al复合材料中引入弥散的Al_4C_3和Al_2O_3质点可以明显提高复合材料的室温和高温强度,随加入C含量的增加或Al粉氧化时间的加长,复合材料的强度提高.在Al_4C_3/Al复合材料的基础上加入SiC颗粒可以提高复合材料的弹性模量并进一步降低其热膨胀系数.复合材料断口为大韧窝加细小韧窝的混合断口,随复合材料基体强度的增加,拉伸断口上断裂的SiC颗粒数量增多. 相似文献
4.
对机械合金化制备的Al_4C_3、Al_2O_3弥散质点和SiC颗粒复合强化Al基复合材料进行了拉伸试验和断口分析,并测定了弹性模量和热膨胀系数.研究表明,在SiC_p/Al复合材料中引入弥散的Al_4C_3和Al_2O_3质点可以明显提高复合材料的室温和高温强度,随加入C含量的增加或Al粉氧化时间的加长,复合材料的强度提高.在Al_4C_3/Al复合材料的基础上加入SiC颗粒可以提高复合材料的弹性模量并进一步降低其热膨胀系数.复合材料断口为大韧窝加细小韧窝的混合断口,随复合材料基体强度的增加,拉伸断口上断裂的SiC颗粒数量增多. 相似文献
5.
利用原子力显微镜观察了纯铝基复合材料早期腐蚀过程中表面形貌的变化特征,研究了SiCw/Al和Al18B4O32w/Al两种复合材料的腐蚀行为,结果表明,两种复合材料在3.5%NaCl溶液中具有明显的点蚀倾向,且随腐蚀时间的增加,点蚀抗的尺寸显著增大,观察发现晶须与基体的界面是腐蚀易于发生的地方,点蚀首先在晶须的端部产生,随后沿着晶须与基体的界面扩展,SiCw/Al和Al18B4O33w/Al复合材料的界面腐蚀机制存在较大的差别,这主要是由于二者界面结合状态不同造成的。 相似文献
6.
《Acta Materialia》2000,48(8):1763-1774
High-strain-rate superplastic behavior of powder-metallurgy-processed 2124 Al matrix alloy and 10%, 20% and 30% SiC particulate reinforced 2124 Al composites were investigated over the temperature range from 370°C to 565°C, and the strain rate range from 10−4/s to 1/s. The true activation energy for the plastic flow after threshold stress compensation was close to that for lattice diffusion in aluminum for the 2124 Al alloy, while the activation energies for the 2124 composites were considerably higher than those for the unreinforced alloy, increasing with an increase in the volume fraction of SiC. The strength of the 2124 Al composites is lower than the strength of the 2124 Al alloy at high temperatures. The strength differential between the unreinforced and reinforced 2124 Al alloys is a function of temperature and is seen to decrease systematically with decrease in temperature and virtually vanishes at 460°C. Particle weakening is discussed in the light of load transfer effect, interphase diffusion, dissolution of second phase particles into matrix and the presence of liquid phase. It is proposed that interphase weakening, possibly with some liquid formation, is the principal factor contributing to the results obtained. Interphase and boundary sliding is believed to be the rate-controlling process in plastic flow of the SiC/2124 Al composites. 相似文献
7.
1. IntroductionHigh specific stiffness and strength, good fatigue properties and tribological propertiesmake SiC whisker reinforcement aluminum composite as attractive class of candidates formany applications such as aerospace and electronic industries[1--2]. As structural componellts with temperature variable the materials used must have good performance includingnot only high mechalilcal properties, but also lower and stable coefficients of thermal expansion. Therefore, it is very important… 相似文献
8.
Effect of aging treatment on mechanical properties of (SiCw+SiCp)/2024Al hybrid nanocomposites 总被引:1,自引:1,他引:1
1 Introduction Metal matrix composites(MMCs) have received much attention because of their improved specific strength, good wear resistance and higher thermal conductivity [1?3]. Up to now, most investigators have studied the fabrication process and mecha… 相似文献
9.
Galvanic coupling effect on the corrosion of SiC-reinforced aluminum alloy-matrix composites was investigated in a sodium chloride solution. The potentiodynamic polarization measurement indicated that pitting potentials of metal matrix composites (MMCs) and AA2124 matrix alloy were similar, and pitting potential of MMCs was almost same as corrosion potential, while pitting susceptibility of MMCs was higher than that of AA2124 alloy. Galvanic current by formation of galvanic couple between SiCw and matrix reveals very low value because of large cathodic polarization of SiC. However, by increasing potential of matrix to pitting potential by this galvanic couple and thus, forming pits easily at the weak passive film near SiC reinforcing phase preferentially, it is concluded that pitting susceptibility of MMCs increases highly than AA2124 alloy of matrix composition. 相似文献
10.
J.M.Yang J.C.Lei J.P.Li P.Cheng Dept. Mater.Sci.and Eng. Xi'an Institute of Technology Xi'an China 《金属学报(英文版)》1999,12(5):1130-1135
1.IntroductionBAS(BaOAl2O3SiO2)glassceramicswithcelsianasmaincrystallinephasearepotentialmatricesofrefractoryfiberorwhiskerreinforcedcompositesduetothehighmeltingpoint(1760℃)andgoodoxidationresistanceofcelsian.Celsianwithmonoclinicstructureisstab… 相似文献
11.
研究了SiCW/Y-TZP/Al2O3系复合陶瓷的显微结构及其力学性能,通过透射电镜拉伸试样中的裂纹扩展形态与组织变化,分析了晶须与ZrO2相变增韧机制。结果表明,陶瓷体内各相结合致密,分布较为均匀,其室温强度和断裂韧度分别为1100MPa和11.9MPa.m^1/2,晶须拔出,裂纹偏转及ZrO2t-m相变是该复合材料的主要增韧机制。SiC晶须和Y-TZP的共同作用,对复合材料强度和断裂韧性的提高 相似文献
12.
The effect of thermal cyclings on mechanical properties at room and some elevated temperatures of SiC whisker-reinforced magnesium-matrix
composites produced by squeeze casting and hot extrusion are clarified. Subsequent thermal cycling produces internal stress
at the matrix/SiC whisker interfaces causing fatigue. The mechanical properties of composites are more influenced by the low
thermal cycling of 298 K— 77 K than the high thermal cycling 673 K—298 K. The high thermal cycling of 673 K—298 K has only
a slight affect on such mechanical properties as tensile strength and proof stress at temperatures lower than 473 K. However,
at 473 K and 573 K, the thermal cyclings there almost no influence on the mechanical properties of SiC whisker reinforced
AE42 alloy-matrix composites. 相似文献
13.
Sajjad Amirkhanlou Roohollah Jamaati Behzad Niroumand Mohammad Reza Toroghinejad 《Journal of Materials Processing Technology》2011,211(6):1159-1165
A major challenge in achieving the best potential of SiCp-reinforced aluminum composites is to homogeneously disperse SiC particles within the aluminum alloys. The presence of coarse Si fibers with non-uniform distribution in cast Al-Si alloys, which may lead to poor mechanical properties, is another important problem that limits the application of these alloys. In order to eliminate these problems, accumulative roll bonding (ARB) process was used in this study as a very effective method for improving the microstructure and mechanical properties of the Al356/SiCp composite. It was found that when the number of ARB cycles was increased, the uniformity of the Si and SiCp in the aluminum matrix improved, the Si particles became finer and more spheroidal, the free zones of Si and SiC particles disappeared, the porosity of composite decreased, the bonding quality between SiCp and matrix improved, and therefore mechanical properties of the composites were improved. The microstructure of the manufactured Al356/SiCp composite after six ARB cycles indicated a completely modified structure so that its tensile strength and elongation values reached 318 MPa and 5.9%, which were 3.1 and 3.7 times greater than those of the as-cast composite, respectively. 相似文献
14.
15.
采用凝胶注模法制备SiC预制件用于无压熔渗液态铝合金实现60~67 vol%SiCp/Al复合材料的近净成形制备,研究了碳化硅颗粒级配及热处理对复合材料力学和热学性能的影响.结果表明:不同粒度的SiC粉体在铝基体中分布均匀,无明显偏聚现象;采用较细的SiC颗粒级配和退火处理都能有效提高复合材料强度;粗颗粒级配能增大SiC在复合材料中的体积分数,有利于导热性能的提高和热膨胀系数的降低;SiCp/Al复合材料抗弯强度介于240~365 MPa,室温时热导率介于122~175 W·m-1·℃-1.之间,室温至250℃的平均线热膨胀系数小于7.5×10-6℃-1,满足电子封装的性能要求. 相似文献
16.
目的 研究SiCp/Al复合材料切削过程中的表面损伤形成机制。方法 以SiCp/Al复合材料为研究对象,展开基于二维切削的仿真和实验研究,建立了包含铝合金2A14、SiC增强颗粒以及界面特性的SiCp/Al切削仿真模型,对作用于不同Si C颗粒部位的材料表面缺陷进行分析;接着利用高速直线电机搭建能映射二维切削条件的实验平台,在不同材料去除条件下,利用扫描电子显微镜和白光干涉仪对切削表面形貌进行测试,分析和验证切削表面损伤形成条件。结果 SiCp/Al复合材料切削表面损伤机理取决于SiC颗粒相对刀具切削路径的位置:当刀尖作用在Si C颗粒的顶部时,表面损伤主要为基体撕裂、颗粒破碎;当刀尖作用在Si C颗粒的中部时,表面损伤为颗粒破碎导致的裂纹和凹坑;当刀尖作用在Si C颗粒的底部时,表面损伤为颗粒拔出导致的凹坑。随着切削深度的增大,凹坑逐渐增多,表面粗糙度随之增大。结论 利用二维切削模型仿真方法和高速直线电机实验,可以有效研究复合材料切削损伤形成机制。Si C颗粒相对刀具切削路径的位置不同会导致切削损伤不同;SiCp/Al复合材料表面质量会随着切削速度的提升而有所提高。 相似文献
17.
晶须对铝基复合材料应力腐蚀开裂行为的影响 总被引:2,自引:1,他引:1
采用双悬臂梁试验,研究了碳化硅晶须增强纯铝基及碳化硅晶须增强2024铝基复合材料和2024铝合金在3.5%NaCl溶液中的应力腐蚀(SCC)开裂行为,探讨了晶须对复合材料应力腐蚀开裂行为的影响。结果表明,晶须的存在改变了材料的应力腐蚀特性,晶须在复合材料应力腐蚀开裂过程中具有促进和阻碍应力腐蚀裂纹扩展的双重作用。 相似文献
18.
ZHANG Wenlong ZHANG Mu GU Mingyuan WANG Dezun and YAO Zhongkai) State Key Lab of MMCs Shanghai Jiaotong University Shanghai China) School of Materials Science Engineering Harbin Institute of Technology Harbin China 《稀有金属(英文版)》2003,22(4)
SiCw/Al composite was fabricated through a squeeze cast route and cold rolled to about 30%, 50% and 70% re-duction in thickness, respectively. The length of whiskers in the composite before and after rolling was examined using SEM. Some of the rolled composites were recrystallization annealed to remove the work hardening of matrix alloy. The tensile strength of the rolled and annealed SiCw/Al composites was examined and then associated with the change of the whisker length and the work hardening of matrix alloy. It was found that the tensile strength is a function of the degree of cold rolling. For the cold rolled composites, with the increase in the degree of cold rolling, the tensile strength increases at first, and decreases when the degree of cold rolling exceeds 50%. For the annealed ones, however, the tensile strength de-creases monotonously with the increase in rolling degree. The different changes in tensile strength between the rolled and annealed composites could be attributed to the result of 相似文献
19.
GUO Shuqi HAN Guihuan YAO Zhongkai Harbin Institute of Technologh Harbin China YAO Zhongkai Dept.of Metals Technology Harbin Institute of Technology Harbin China 《金属学报(英文版)》1989,2(9):189-194
This paper presents an investigation on the microstructures and properties of the17v.-% SiCw/Al-12Si composites.TEM observations and EDAX analysis revealed that Aldiffuses into the SiC whiskers and that dislocations exist at the whisker/matrix interfaces.Tensile test results showed that the isothermal exposure and thermal cycle at both 573K and733 K caused the UTS reduction of the composites,and the reduction in UTS due to thermalexposure at 733 K was much more significant than that due to thermal cycle at the same tem-perature.The SiC_W/Al-12Si composites were also found to have exellent wear resistance,which does not seem to vary much with the volume content of whiskers in the ronge of 11—17%. 相似文献
20.
预制块制备对挤压铸造SiCW/ZM5复合材料性能的影响 总被引:10,自引:1,他引:9
制备了含不同粘结剂的SiC晶须预制块,并采用挤压铸造法制备出含不同粘结剂的SiCw/ZM5镁基复合材料,对其组织结构和力学性能进行了研究。结果表明,采用含酸性磷酸铝粘结剂制备的SiCw/ZM5镁基复合材料的性能最佳,这可能和粘结剂与晶须以及基体合金的界面反应有关 相似文献