Al_2O_3纤维增强铝基复合材料储能焊接头微观组织分析

Microstructure analysis on capacitor discharge welded Al_2O_3 fiber reinforced Al-matrix composites joint

应用自制微型储能电阻焊机对Al_2O_3纤维增强铝基复合材料进行了点焊连接,分析了接头的组织形貌。在储能焊接头中形成了规则的扁平熔核,复合材料基体与熔核金属过渡良好。极短的焊接时间和大的冷却速率使共晶Si显著细化。细小的共晶Si颗粒均匀分布于铝基体中,形成与MMCs不同的基体组织。少量Al_2O_3纤维发生了一定程度的破碎,大部分纤维仍保持其原有的形貌特征,随机分布于熔核金属基体中。适当增大电极压力,焊前对复合材料做除氢处理并保持干燥是减小和消除气孔、提高和改善MMCs储能焊接头质量的有效途径。

The resistance spot welding of the Al2O3 fiber reinforced Al-matrix composites (MMCs) was conducted using a micro-type capacitor discharge welding machine and the microstructural morphology of the joint was investigated. The results showed that a regular, flat nugget was formed in the joint and the microstructural transition from nugget to matrix was rather well. Due to the very short welding time and high cooling rate, the eutectic Si was refined remarkably. The tiny eutectic Si particles distributed uniformly in the Al-matrix, resulting in microstructure different from the MMCs. Small quantity of Al2O3 fibers were broken down to some extent, while most of them remained their original morphology, distributing in the nugget matrix randomly. It was considered an effective way to eliminate the porosity and improve the joint quality, i. e. increasing electrode pressure properly, removing hydrogen from MMCs and holding the MMCs dry.