中文摘要：

采用切片法，对3mm厚2024铝合金和AZ31镁合金异种金属搅拌摩擦连接对接接头从截面和表面两个方向逐步层切，对每一截面抛光、腐蚀、拍照，并通过二维图像对接头进行了简单的三维重构，从而确定了3mm厚铝／镁合金异种搅拌摩擦连接接头的金属材料流动状况。结果表明，接头垂直方向不同层面的金属流动模式不同，同一层面前进侧和后退侧关于对接中心线材料流动也不对称。锯齿间距等于进给速度和搅拌头转速的比值表明，搅拌头每旋转一周，材料在搅拌头后部完成一次堆积。接头中下部的孔洞缺陷是由材料流动不充分造成的。低转速进给速度比的工艺参数使得材料流动主要发生在水平层面。

英文摘要：

Slicing method was adopted to observe different layer for 3 mm AZ31 magnesium and 2024 aluminum alloy dissimilar friction stir butt joint from section and surface directions. Each section was polished, etched and taken photograph under optical microscope. The material flow status of dissimilar friction stir joint for 3 mm Mg and Al alloys was confirmed by the 3D reconstructure which synthesised from 2D joint images. The results showed that the metal flow pattern of the joint was different on various layer and the flow was not symmetric about the weld centerline on each layer. The zigzag spacing of joint appearance was equal to the ratios of feed and rotation speed, which showed that the material accumulation was completed on the back of the tool once the tool rotated a circle. The formation of the hole defects at the middle and lower part of the joint was caused by the inadequate material flow. The flow of the material mainly occurred in horizontal planes was due to the low ratio of feed and rotation speed.