机械合金化—放电等离子烧结原位制备纳米晶Al-Fe复合材料

发布时间：2019-04-09 08:40

【摘要】：Al和Fe是地壳中储量最为丰富的2种金属元素,其合金具有质量轻、组织结构稳定性高、原料丰富和价格低等许多优良的性能,可以作为轻质高强结构件,大大降低重量和成本,在汽车、航空航天、海洋、国防和军工等领域具有广阔的应用前景。本文采用机械合金化-放电等离子烧结(Mechanical Alloying-Spark Plasma Sintering,MA-SPS)工艺原位制备了接近理论密度的纳米晶Al-Fe复合材料,利用X射线衍射(X-Ray Diffraction,XRD)、扫描电子显微镜(Scanning Electron Microscope,SEM)、透射电子显微镜(Transmission Electron Microscope,TEM)和能谱仪(Energy Dispersive Spectrometer,EDS)等分析测试技术对粉末及烧结试样的物相组成、组织结构和成分分布进行了表征,并检测了烧结试样的显微硬度、压缩性能和拉伸性能等相关力学性能,系统研究了MA关键工艺参数-磨球级配和Fe含量对材料组织结构及性能的影响。主要研究成果如下:采用MA-SPS技术原位制备了接近理论密度的Al13Fe4/Al复合材料,增强相金属间化合物Al13Fe4以三种形态存在于α-Al基体中:大颗粒(1~2μm)、交错分布的短棒状超细颗粒(0.1~1.0μm)和纳米颗粒(~20nm)。其中,前两种形态Al13Fe4相原位生成,后一种纳米颗粒Al13Fe4相固溶析出生成。采用磨球级配对材料的微观组织和性能进行了优化。磨球级配处理的烧结试样塑性得到显著提高,最大塑性变形量高达13.6%,这主要归功于其组织中存在大量的大颗粒α-Al相和超细颗粒Al13Fe4相。Al-2Fe、A-10Fe、Al-12.5Fe(原子百分含量)三组粉末经过80h机械合金化后,Al-10Fe的粉末粒径最小(~10μm);SPS烧结后,制备的Al-10Fe试样具有最优的综合压缩力学性能:显微硬度为227HV(1.2GPa),抗压强度极限为845.8MPa,最大塑性变形量为13.6%。
[Abstract]:Al and Fe are the two most abundant metal elements in the crust. Their alloys have many excellent properties, such as light weight, high structural stability, rich raw materials and low price, which can be used as lightweight and high strength structural parts. Greatly reduce the weight and cost, in the automotive, aerospace, marine, national defense and military industry and other fields have a wide range of applications. Nanocrystalline Al-Fe composites close to theoretical density were in situ prepared by mechanical alloying-spark plasma sintering (Mechanical Alloying-Spark Plasma Sintering,MA-SPS) process. X-ray diffraction (X-Ray Diffraction,XRD) was used to fabricate nanocrystalline Al-Fe composites. Scanning electron microscope (Scanning Electron Microscope,SEM), transmission electron microscope (Transmission Electron Microscope,TEM) and energy dispersive spectroscopy (Energy Dispersive Spectrometer,EDS) were used to characterize the phase composition, microstructure and composition distribution of powder and sintered samples. The mechanical properties such as microhardness, compressive properties and tensile properties of sintered samples were tested. The effects of grinding ball gradation and Fe content on the microstructure and properties of MA were systematically studied. The main results are as follows: in-situ Al13Fe4/Al composites with close theoretical density were prepared by MA-SPS technique. The reinforced intermetallic compound Al13Fe4 exists in 伪-Al matrix in three forms: large particles (1 ~ 2 渭 m), Interlaced short rod-like ultrafine particles (0.1 ~ 1.0 渭 m) and nano-particles (~ 20nm). The first two forms of Al13Fe4 phase were formed in situ, and the latter one was formed by solid solution precipitation of nanoparticles Al13Fe4 phase. The microstructure and properties of grinding ball pairing materials were optimized. The plasticity of sintered samples treated with grinding ball gradation was improved significantly, and the maximum plastic deformation was up to 13.6%. This is mainly due to the large amount of 伪-Al phase and ultra-fine Al13Fe4 phase in the microstructure. Al-2Fe,A-10Fe, After 80 h mechanical alloying of Al-12.5Fe powder, the particle size of Al-10Fe powder was the smallest (~ 10 渭 m). After sintering with SPS, the prepared Al-10Fe samples have the best comprehensive compressive mechanical properties: the microhardness is 227HV (1.2GPa), the compressive strength limit is 845.8 MPA, and the maximum plastic deformation is 13.6%.
【学位授予单位】：华中科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB331

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