Fabrication of Porous Aluminum Alloys with Aligned Unidirectional Pores by Dipping Pipes into Liquid and Semi-solid base Metals

Abstract

The new fabrication method to fabricate porous aluminum alloys with aligned unidirectional pores was invented by dipping pipes into semi-solid slurry. Pure aluminum pipes were dipped into Al-4mass% Cu liquid and semi-solid slurry of base metal in an electric furnace. The base metal and dipped pipes were cooled and solidified together in the air. The pipes were bonded to the base metal and the original shape of the pipes was maintained by using the semi-solid slurry of the base metal. However, pipes are usually ruptured and buried in the liquid base metal during the process. On the other hand, it is possible to avoid the rupturing of pipes by using the semi-solid slurry because thermal damage of pipes can be reduced by an increase in solid fraction of the base metal. The analysis results of Electron Probe MicroAnalyser showed that Cu diffused into grain boundaries of pipes, which decreased the melting temperature of surface of pipes. As a result, the α phase melted partly and then the pipes were bonded with the base metal metallurgically. This dipping method can fabricate porous Al-Cu alloys with aligned unidirectional pores with porosity of 33% when nineteen pipes are used.