【作者】 任阔；

【导师】 郑治祥； 吴玉程；

【作者基本信息】 合肥工业大学 ， 材料学， 2009， 硕士

【摘要】 弥散强化铜基复合材料以其优异的性能而有着广泛的应用前景。虽然采用原位氧化法制备的弥散强化铜基复合材料性能优于其它众多的制备方法,但是目前尚存在工艺复杂、成本昂贵等问题。机械合金化(MA)作为一种制备弥散强化复合材料的方法,可以导致硬质稳定相弥散分布的细而均匀。本文对用MA法制备的Cu-Cr-(Zr)弥散强化铜基复合材料进行了实验研究,结果表明:MA是制取弥散强化铜基复合材料比较简单、成本较低的一种方法;制备的弥散强化铜基复合材料不仅硬度和导电率较高,而且耐磨性能也好。另外,还对MA的工艺参数进行了研究,理论分析和实验结果表明:(1)采用机械合金化技术制备了Cu-Cr复合粉体,利用XRD分析了Cu-Cr复合粉体机械合金化过程。结果表明:随着球磨时间的增加,晶粒不断细化,Cu-Cr复合粉末衍射峰逐渐宽化,衍射强度逐渐下降;经球磨60h后,Cr大部分固溶在Cu晶格中。(2)采用粉末冶金的方法制备了颗粒增强铜基复合材料,分析了不同球磨时间和不同颗粒含量对铜基复合材料力学性能的影响,结果表明:随着球磨时间的延长和Cr含量增多,铜基复合材料的硬度和抗弯强度提高,但导电性能下降。(3)采用冷压-烧结-复压-复烧工艺对Cu-Cr合金粉末致密化过程进行研究。系统探讨了压制压力、烧结温度对相对密度的影响。研究结果表明初压和复压能显著提高材料相对密度,复烧进一步提高材料的相对密度,其作用主要体现在材料性能的改善和优化。(4)由Cu-Cr-Zr和TiC混合粉末经机械球磨后,再经退火、压制、烧结、复压、复烧制备成TiC弥散强化铜基复合材料。该体系的最佳烧结温度为950℃,该材料具有均匀的显微组织和良好的性能。该材料的相对密度和导电性随球磨时间的延长和TiC含量的增高而降低,但其硬度却随球磨时间的延长和TiC含量的提高而增大。(5)在M-200型销-盘式摩擦磨损试验机上进行了Cu-Cr-Zr/TiC合金的干滑动摩擦磨损实验,研究了TiC颗粒含量的改变对合金磨损率的影响,并用扫描电子显微镜和X射线能谱对其磨损表面形貌及试样亚表层的微观形貌进行观察分析。结果表明,合金的磨损率随TiC含量的增加而下降;合金的磨损形式主要有粘着磨损和磨粒磨损,试样表面不断的滑动摩擦行为在合金的亚表层形成了高度集中的塑性变形区。基体金属的磨损主要呈现出显微切削和犁沟特征,而金属陶瓷的流失形式主要表现为界面处TiC颗粒的脱落。更多还原

【Abstract】 Copper matrix composites have a bright application future. Although the properties of the composite is made by IN-SITU method are much better than the others, there are still some problems such as complicated technics and high cost etc. Mechanical alloying(MA) is a method of producing dispersion strengthened composites, which makes the dispersion fine and harmony. In this paper MA was used to produce Cu-Cr-(Zr) composites. The results show that MA is a simple and economical means and that the achieved dispersion reinforced copper composites possess high hardness,electric conductivity and high wear resistance. Also, the processing parameters of MA were studied. The theoretical analysis and experimental results indicate:(1) In this paper mechanical alloying was used to make Cu-Cr composites powder. XRD was used to study the mechanical alloying processed Cu-Cr powder. It showed that: with the increasing of ball-milling time, Cu-Cr powder particle and grain become smaller and smaller, and the X-ray diffraction peaks of both copper and chromium become broader and their intensity diminishes. Cu-Cr super saturation solid solution was obtained by 60h milling.(2) Powder metallurgical method was used to manufacture particle reinforced copper matrix composites, and the influence of particle content on composite properties was analyzed. The results showed that mechanical properties,such as hardness and bending strength of the composite increased with increasing milling time and Cr content, but conductivity of composite was reduced.(3) Densification Process of Cu-Cr alloy powders was studied by means of cold pressing-sintering- repressing-resintering method. The influence of different pressure and temperature on the relative density was discussed systematically. The results showed that pressing and repressing can significantly improve the relative density, however, resintering did not evidently contribute to the relative density, and its main role reflected in the performance improvement and optimization.(4) TiC-dispersion-strengthened Cu-based composite powder has been prepared with Cu-Cr-Zr and TiC powders by MA. The composite powder was used to make composite material by annealing,pressing,sintering, e-pressing,re-sintering process. The Suitable sintering temperature for Cu-Cr-Zr/TiC system is 950℃. The material possess uniform microstructure and better properties. Relative density and conductivity of the composite material decreased with increasing milling time and TiC content. But the mechanical property of hardness increased.(5) The friction and wear behavior of Cu-Cr-Zr/TiC alloys dry sliding against a brass counterface was investigated on a M-200 pin-on-disk wear tester. The worn surface of Cu-Cr-Zr/TiC alloy was studied by using of SEM and EDS. The results indicated that the wear rate of aged Cu-Cr-Zr/TiC alloy decreased monotonically with the increase of TiC content. Adhesive wear and abrasive wear were the dominant wear mechanisms under unlubricated condition. With continuous loading and sliding, plastic deformation intensified and thus formed a layer with fragmented microstructure and an concentrated plastic deformation zone in subsurface region. The wear mechanisms of the composite include ploughing and spalling of some carbide particles on the worn surfaces. The spalling of TiC micro-particles at the interface has significant influence on the wear resistance of the composite.更多还原