【作者】 刘刚；

【导师】 胡津；

【作者基本信息】 哈尔滨工业大学 ， 材料学， 2006， 硕士

【摘要】 利用脉冲YAG激光器对Al₁₈B₄O₃₃w/2024Al复合材料表面进行激光处理。研究了激光功率、扫描速率及脉冲宽度对复合材料表层组织及电化学腐蚀行为的影响规律。采用透射电子显微镜及小角掠入射X-射线衍射仪研究了Al₁₈B₄O₃₃w/2024Al复合材料的微观组织结构。采用扫描电镜观察了Al₁₈B₄O₃₃w/2024Al复合材料表面激光层组织。观察了激光处理复合材料表面各种微观组织结构的变化。激光处理后,复合材料表面上的晶须发生了分解,观察了基体中的共晶相以及析出相,研究了晶须的不同分解产物,激光熔化层中的主要相是铝及分解产物Al₂O₃。结果表明,激光工艺参数对复合材料表层组织及腐蚀行为有较大的影响。激光处理后复合材料的腐蚀电位得到较大的提高。复合材料腐蚀抗力的增加被认为是增强体晶须的分解以及金属间化合物CuAl₂的消失。它们被发现是点蚀形核的位置。最佳激光工艺参数处理的试样展示出比其它激光处理试样更大的耐蚀性,这主要归功于在激光层中形成了均匀、致密、无缺陷的微观组织。更多还原

【Abstract】 A pulsed YAG laser installation was used to produce surface treatment on Al₁₈B₄O₃₃w/2024Al composite. The effect of laser power, laser scanning rate and pulse duration on the microstructures and corrosion behaviors of the composites has been studied.The microstructure of a laser treated Al₁₈B₄O₃₃w/2024Al composite has been investigated using transmission electron microscope （TEM）, low-angle （glancing angle） X-ray diffraction （XRD） techniques.Various surface microstructures were observed in the laser treated composite. The Al₁₈B₄O₃₃ whisker on the surface of the composite was decomposed during laser surface melting, various decomposition produces were studied in the laser treated composite. Eutectic phases and the precipitation in the matrix of the composite with laser-treated were observed. The main phases detected in the molten zone were aluminum and decomposition produces Al₂O₃.Results indicate that laser power has significant influences on both of the microstructure and the corrosion resistance. The difference in morphological transformations was observed on the surfaces of the laser-treated specimens. An increase in Epit was obtained after laser-treated for the composite. The improvement was considered primarily due to the reduction both ofreinforcement Al₁₈B₄O₃₃ whisker and intermetallics CuAl2 on the surfaces of the laser-treated composites, which were found to be sites for pits nucleation. Moreover, the specimen with the optimal laser parameter treated exhibited a much greater resistance to corrosion than the other specimens with laser treated. This was attributed to the formation of the homogeneous and defect free microstructure in the laser-modified layer.更多还原