【作者】 丛培军；

【导师】 赵宇光；

【作者基本信息】 吉林大学 ， 材料加工工程， 2007， 硕士

【摘要】 本文在空气环境中,借助于添加适量的助渗剂K2TiF6实现了Al-Si合金熔体对VFe松散堆积床的无压反应浸渗,成功地制备了AlFeSi、AlSiV增强的铝基复合材料。实验中采用了上置法和浇注法两种方法制备铝基复合材料。分析了熔体向松散堆积床浸渗的动力学过程,指出无压反应浸渗过程中存在元素的扩散、生成物的扩散以及各元素之间的化学反应等过程;列出了通常无压浸渗实验所必备的条件并分析其原因,对无压浸渗过程中的影响因素,例如浸渗温度、浸渗时间和助渗剂等因素进行了实验研究和分析,着重分析了助渗剂K2TiF6的作用机制。分析了本实验无需在N2保护下、实验中不能由Mg元素参加的原因,在此基础上,优化并给出适合于大气条件下进行无压反应浸渗的工艺参数。通过对无压反应浸渗法所制备的复合材料进行硬度测试和磨损性能的测试,为此方法制备的复合材料的可用性提供依据。更多还原

【Abstract】 Metal matrix composites is a new material which is produced by joining another material or reinforcement into one metal. Intermetallics reinforced Aluminium matrix composites have many excellent and unique properties, such as high specific strength and stiffness, low heat expand modulus and good wear resistance, and therefore, increasing attention has been paid to it in automotive, communication apparatus and aerospace applications. In order to get metal matrix composites with better properties , various means have been investigate and invent by many people, pressueless infiltration is a good technique.The pressureless infiltration technique means that metal liquid infiltrate into preform spontaneously by capillary, metal matrix composites are produced finally. At the same time there are reactions between elements. This technique offers the potential to be an alternative, simple, low-cost processing route for the manufacture of near-net shape silicon carbide reinforced aluminum matrix composites. But it also has many disadvantages, such as the poor wetting between ceramic and metal, under the atmosphere protect of N2 or Ar, the long time and low rate of infiltration, the difficult control of volume fractions of ceramic particulates, and so on. Therefor, many works should be done to research infiltration mechanism, reduce limited conditions, improve atmosphere, get better Microstructure finally.The major research purpose is to simplify the pressureless infiltration process. Making pressureless infiltration happen under air condition, and the process happen rapidly, get fine intermetallic reinforced Al matrix composites at last. The major research efforts of the present study are as follows:(1)AlFeSi,AlSiV reinforced aluminium matrix Composites by pressureless reactive infiltrationAlFeSi,AlSiV reinforced aluminium MMCs in the present study were produced successfully by pressureless infiltration technique based on the experiment research. The process is that the pressureless or spontaneous infiltration of Al-Si alloy into the loose bed in air contains K2TiF6.(2)Analyze microstructure of composites produced by pressureless reactive infiltrationThere are two kinds of reinforcements in the composites produced by pressureless reactive infiltration. One reinforcement like diamond is AlFeSi of AlSiV; another reinforcement like needle isβ-Al5FeSi;(3) Hardness and abrasive wear behavior of composites produced by pressureless infiltrationThe hardness of composites increased greatly compared with Al-13Si especially on the surface. The material shows great wear resistance because there are many reinforcements in the surface of composites.(4) Decrease limited condition of pressureless reactive infiltrationThrough dynamics analysis of melt penetrating into loose bed, it can be concluded that most pressureless infiltration experiments must include Mg under N2 because of non-wetting between liquid and solid. There are two wetting system in this experiment: Al-Si and VFe. So it is no need to include Mg and N2 in the experiment, and the limited condition is decreased.(5) Results of infiltration under different conditionsIt is concluded that AlSi infiltrates into VFe successfully when the system is heated to 650℃or preserved for 5mins under 800℃. The best microstructure is found when the system is preserved for 30mins under 800℃. (6)Mechanism of K2TiF6 function in the processThe system must include K2TiF6 if there is no N2. It is analyzed that liquid metal penetrate Al2O3 on the surface of Al liquid, so Al and K2TiF6 reactive . Heat the reaction released and KF,AlF3 reaction created dissolves Al2O3 rapidly. So AlSi and VFe contact the infiltration takes place.更多还原