SiCp/AZ61镁基复合材料的热膨胀性能研究

采用高能超声方法制备了SiCp增强镁基复合材料。论述了增强体、温度、增强体颗粒尺寸、增强体体积分数等对镁基复合材料热膨胀性能的影响。结果表明,增强体的加入可以减小镁基复合材料的热膨胀系数,镁基复合材料的热膨胀系数随温度的变化而变化,增强体的颗粒尺寸越小、体积分数越高,镁基复合材料的热膨胀系数就越小。     

颗粒尺寸对SiCp/Mg复合材料热膨胀性能的影响

设计并采用真空气压浸渗法制备了不同颗粒尺寸的高体积分数SiCp/AZ91D镁基复合材料,研究了颗粒尺寸对镁基复合材料热膨胀性能的影响.结果表明,改变颗粒尺寸是调节镁基复合材料热膨胀性能的一种非常有效的手段.相同体积分数复合材料的热膨胀系数随颗粒尺寸的减小而逐渐降低,不同体积分数的SiCp复合材料的热膨胀系数与复合材料的界面面积成反比关系;减小颗粒尺寸与提高颗粒体积分数一样,能有效降低复合材料的热膨胀系数;颗粒尺寸对镁基复合材料热膨胀性能的作用机制主要是通过复合材料的界面面积、致密度及其镁基体的位错密度来实现的.     

颗粒增强镁基复合材料的增强复合新思路

从颗粒增强镁基复合材料的性能和应用、复合反应的强化机理及界面状况、研究进展、影响颗粒增强镁基复合材料性能的因素、选择增强体和镁合金基体时应考虑的问题几个方面对颗粒增强镁基复合材料的发展情况进行介绍,并展望了今后的发展前景。     

原位镁基复合材料的研究进展

重点介绍了原位颗粒增强镁基复合材料的制备技术、原位增强体的形成机制、增强机理和原位镁基复合材料的力学性能等研究热点问题并展望了原位颗粒增强镁基复合材料的发展趋势。     

原位合成增强镁基复合材料的制备方法

镁基复合材料以高强度、高弹性模量的陶瓷颗粒或硬质相为增强相,从而具有好的力学性能和物理性能。原位合成法增强镁基复合材料中的增强体具有热稳定性好、组织细小、与镁基体界面结合良好等优点,因而原位合成法成为制备镁基复合材料研究发展的方向之一。本文重点介绍了原位颗粒增强镁基复合材料的制备方法以及其优缺点,并分析了原位制备镁基复合材料过程中存在的问题,展望了发展趋势。     

原位颗粒增强镁基复合材料的制备

综述了原位颗粒增强镁基复合材料的研究进展，重点介绍了原住反应法制备颗粒增强镁基复合材料的基本原理和过程，并分析了其组织和性能；同时还简述了传统铸造法制备原位颗粒增强镁基复合材料的特点。最后，对原位颗粒增强镁基复合材料的发展趋势作了展望。     

颗粒增强镁基复合材料的制备技术与展望

介绍了颗粒增强镁基复合材料的制备方法,包括粉末冶金法、喷射沉积法、搅拌铸造法、熔体浸渗法和原位合成法等。阐述了各种制备方法的应用背景、基本原理以及应用情况,讨论了不同制备方法对复合材料的强度、耐磨性、耐蚀性等性能以及气孔率、杂质含量等缺陷的影响,评价了各种制备工艺的优缺点,剖析了各种制备方法的异同。结果表明,影响颗粒增强镁基复合材料性能的关键问题在于如何使增强体在基体中均匀弥散分布,展望了颗粒增强镁基复合材料的制备技术。     

颗粒增强镁基复合材料的研究进展

综合评述了颗粒增强镁基复合材料的国内外研究进展情况,并对其增强机制、制备方法、力学性能等方面进行了分析和介绍。最后指出了制备颗粒增强镁基复合材料存在的问题,并提出了展望。     

超声波辅助液态法制备铝基复合材料的研究进展

简要介绍了超声波在液态法制备颗粒增强铝基复合材料中的作用,高能超声波除了可净化铝熔体及细化晶粒外,还可改善铝基体与增强体的润湿性、提高界面结合强度、促进增强体的分散性和控制反应生成的增强体颗粒尺寸。重点概述了超声波辅助原位反应法和外加法制备颗粒增强铝基复合材料的最新研究进展,总结了当前超声波辅助液态法制备铝基复合材料所遇到的问题,并展望今后的研究方向。     

准晶增强铝基复合材料的微观组织及热膨胀行为

以铝粉(+200目)为基体、准晶颗粒(粒度≤30μm)为增强相,采用粉末冶金法制备了准晶颗粒增强铝基复合材料.采用光学显微镜、扫描电镜、能谱分析仪分析了该复合材料的微观组织及界面结合特征,并用TMA设备研究了复合材料在25～500℃的热膨胀行为.XRD和SEM分析结果均证明准晶具有良好的结构和热稳定性.准晶颗粒与Al基体之间存在成分均匀且界面厚度均匀的过渡层(厚度＜1μm),且准晶颗粒在Al基体内均匀分布.TMA结果表明:颗粒尺寸对复合材料的热膨胀系数影响最为显著,当颗粒尺寸为10～30μm时,其线膨胀系数达到最小值16.25×10-6/℃;复合材料的热膨胀系数随着颗粒含量的增加而减小.     

Thermal expansion and dimensional stability of unidirectional and orthogonal fabric M40/AZ91D composites

Unidirectional (60%, volume fraction) and orthogonal (50%, volume fraction) M40 graphite fibre reinforced AZ91D magnesium alloy matrix composites were fabricated by pressure infiltration method. The coefficients of thermal expansion (in the temperature range of 20-350 ℃) and dimensional stability (in the temperature range of 20-150 ℃) of the composites and the corresponding AZ91D magnesium alloy matrix were measured. The results show that coefficients of thermal expansion of the composites in longitudinal direction decrease with elevating temperature. The coefficients of thermal expansion (CTE) for unidirectional M40/AZ91D composites and orthogonal M40/AZ91D composites are 1.24×10-6 ℃-1 and 5.71×10-6 ℃-1 at 20 ℃, and 0.85×10-6 ℃-1 and 2.75×10-6 ℃-1 at 350 ℃, respectively, much lower than those of the AZ91D alloy matrix. Thermal cycling testing demonstrates that the thermal stress plays an important role on residual deformation. Thus, a better dimensional stability is obtained for the AZ91D magnesium alloy matrix composites. More extreme strain hysteresis and residual plastic deformation are observed in orthogonally fabric M40 reinforced AZ91D composite, but its net residual strain after each cycle is similar to that of the unidirectional M40/AZ91D composite.     

Physical,Mechanical, and Tribological Attributes of Stir-Cast AZ91/SiCp Composite

In the present investigation, composites with silicon carbide particle （SiCp） as reinforcement and AZ91 magnesium alloy as matrix have been synthesized using liquid metal stir-casting technique with optimized processing conditions. The composites with good particle distribution in the matrix, and better grain refinement and good interfacial bonding between the matrix and reinforcement have been obtained. The effect of SiCp content on the physical, mechanical, and tribological properties of Mg-based metal matrix composite （MMC） is studied with respect to particle distribution, grain refinement, and particle/matrix interfacial reactions. The electrical conductivity, coefficient of thermal expansion, microas well as macro-hardness, tensile and compressive properties, and the fracture behavior of the composites along with dry sliding wear of the composites have been evaluated and compared with the base alloy.     

Effect of thermal stresses on the thermal expansion and damping behavior of ZA-27/aluminite metal matrix composites

When the fabrication of a metal matrix composite (MMC) involves its cooling from a high temperature, plastic-elastic residual deformation fields can be generated within and around the particle due to the differential thermal expansion between the particle and matrix metal. The present investigation is concerned with the effect of thermal residual stresses on the thermal expansion and damping behavior of aluminite particulate-reinforced ZA-27 alloy MMCs. Composites were prepared by the compocasting technique with 1, 2, 3, and 4 wt.% of aluminite reinforcement. Thermal expansion and damping properties have been studied experimentally as a function of temperature over a temperature range 30 to 300 °C both in the heating and cooling cycle. The thermal expansion studies exhibited some residual strain, which increased with the increase in the weight percent of the reinforcement. The damping capacity of both the composites and matrix alloy is found to increase with the increase in temperature during the heating cycle, whereas in the cooling cycle, damping behavior exhibits a maximum, which becomes more pronounced with the increase in the weight percentage of the reinforcement. The appearance of the maximum may be linked with dislocation generation and motion as a result of plastic deformation of the matrix at the metal/reinforcement interface. This phenomenon is attributed to the thermal stresses generated as a result of coefficient of thermal expansion (CTE) mismatch between the composite constituent phases. The thermal stresses have been estimated in both the cases using simple models.     

镀TiC金刚石/铝复合材料的界面及热膨胀性能

采用气压浸渗法制备高体积分数的镀TiC金刚石/铝复合材料,通过SEM和EDS等手段对复合材料的断口形貌进行分析,并研究TiC镀层对复合材料界面和热膨胀性能的影响。结果表明:TiC镀层改善金刚石颗粒与铝合金基体之间的选择性粘结现象,断裂方式以基体断裂为主。部分TiC会被氧化成TiO2并与铝合金基体反应生成Al2O3,从而实现金刚石颗粒与铝合金基体之间良好的界面结合;TiC镀层有效地降低复合材料的热膨胀系数(CTE),增强复合材料热膨胀性能的稳定性。在体积分数相同的情况下,CTE随金刚石颗粒尺寸的减小而减小。     

Equation for the density of particle-reinforced metal matrix composites: A new approach

This paper presents a novel equation for the density of ceramic particle reinforced metal matrix composites. An overall density change occurs in composites due to the thermal mismatch between the metal matrix and the reinforcement. The thermal mismatch occurs because the coefficient of thermal expansion and the elastic properties are different for the matrix and the reinforcement. The values obtained using the proposed equation for density were compared with both the rule of mixtures for density and the experimental values obtained for aluminium and zinc alloy composites. The composite specimens were fabricated using compocasting technique (one of the types of liquid metallurgy route). The proposed mathematical model is found have better agreement with the experimental results at lower volume fractions of the reinforcement; however, some deviations were observed at higher volume fractions of the reinforcement. The proposed equation yields agreeable results for aluminium composites and fairly agreeable results for zinc alloy composites.     

界面改性对SiCf/Cu基复合材料热膨胀性能的影响

研究了SiCf/Cu基复合材料分别在有无Ti6Al4V界面改性涂层两种情况下的纵向热膨胀行为,并采用扫描电镜对热循环后的试样进行显微形貌观察。结果表明,界面结合强度对纤维增强金属基复合材料的纵向热膨胀行为有很大影响。对于没有Ti6Al4V涂层的复合材料,其热膨胀行为不稳定,在经历连续两次热循环后,其纵向均表现为正的残余应变,原因是基体发生了严重的界面脱粘、滑移和膨胀;而对于有Ti6Al4V涂层的复合材料,其纵向热膨胀系数明显减小,两次热循环后其尺寸保持稳定,纤维/基体界面结合也保持稳定。     

EFFECTS OF HEAT TREATMENT ON THE THERMAL EXPANSION BEHAVIOR OF SiC WHISKER REINFORCED ALUMINUM COMPOSITE

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…     

Estimation of thermal expansion properties of quasicrystalline alloys

By investigating the thermal expansion properties of three quasicrystalline alloys Al65Cu20Cr15 quenched,Al65Cu20Cr15 cast and Al65Cu20Fe15 cast particles reinforced A1 matrix composites from 25℃ to 500℃, the thermal expansion coefficients of three quasicrystalline alloys were theoretically estimated. The results show that the thermal expansion coefficients of the composites are much lower than that of pure A1, and the thermal expansion coefficients of the composites reinforced by Al-Cu-Cr quasicrystalline particles are lower than those of the composites reinforced by Al-Cu-Fe quasicrystalline particles. According to estimating, quasicrystalline alloys have negative thermal expansion coefficients, and the thermal expansion coefficients of Al-Cu-Cr quasicrystalline alloys are lower than those of Al-Cu-Fe quasicrystalline alloys. In the alloys, the more the qusicrystalline content, the lower the thermal expansion coefficient.     

热暴露对SiCf/Ti-6Al-4V复合材料热膨胀行为的影响

研究了热暴露对SiCf/Ti-6Al-4V复合材料热膨胀行为的影响。对基体合金、制备态复合材料、经900 ℃热暴露10, 25及75 h的复合材料的热膨胀行为进行了实验测量。结果表明,无论纵向和横向,热暴露的复合材料其热膨胀系数均高于制备态复合材料。且无论纵向和横向,经900 ℃热暴露10和75 h的复合材料热膨胀系数均高于经900 ℃热暴露25 h的复合材料。这是因为经900 ℃热暴露25 h的复合材料拥有较为合适的界面反应。另外,在对复合材料纵向热膨胀系数进行预测时,因为Schapery模型在整个加热过程中都考虑了热拉伸残余应力对复合材料热膨胀系数的影响,因此在CTE曲线的高温阶段,预测值低于实验值