Formation of Local Metallic Foam of Aluminum Alloy Using Friction Stir Processing

Friction stir welding (FSW) has been receiving considerable attention along with friction stir processing (FSP), which is a new technique based on the principles of FSW. In a recent study by the author, the excellent fluidity of aluminum alloy in FSP was recognized, and metal matrix composites (MMCs) were fabricated by the local dispersion of aluminum oxide particulates in aluminum alloy. In the present study, we propose novel methods for property modification of MMCs, such as the fabrication of local metallic foam of 6061 aluminum alloy by FSP. First, titanium hydride particles (TiH2) were dispersed locally as a foaming material to produce the local MMC. Then, the specimen was heated in an electric oven for local foaming. As a result, the structure of the foam produced in the layers was controlled by the titanium hydride particles dispersed in those layers. By monitoring the heat generated during FSP, we investigated the possibilities of dispersing the foaming material by the heat generating in FSP without the application of additional heat using an electric oven. The result showed that the possibility of local foaming by the heat generated in FSP. However, there are still problems for solution like the control of the maximum heating temperature, and future tasks.