Effect of Die Material on Compressive Properties of Open-Cell Porous Aluminum Fabricated by Friction Powder Compaction Process

Abstract

Porous Al is expected to be used for a variety of applications such as automotive components and building materials owing to its high functionality and light weight.1) Among the numerous fabrication processes of porous Al, the sintering and dissolution process (SDP) is a promising route for fabricating open-cell porous Al.2­8) In this process, a mixture of Al powder and NaCl powder is sintered by applying appropriate pressure and heat using an electric furnace2­5) or by spark plasma sintering (SPS).6­8) Then, the sintered mixture is placed in water to remove the NaCl and obtain porous Al. Recently, a new friction powder compaction (FPC) process, which requires no external heat source for powder sintering, has been developed.9,10) Porous Al can be fabricated by combining the SDP and the FPC process.9) In this combined process, the sintering of the powder mixture is conducted simply by plunging a rotating tool into a die filled with the mixture, and sintering is induced by the friction heat and pressing load generated by the rotating tool plunging into the die. It is considered that the pressing load and temperature during the sintering process directly affect the degree of sintering of the mixture, namely, the mechanical properties of the obtained porous Al. In friction stir welding (FSW), it is known that the welding temperature and load are significantly different in the FSW of Cu and that of Al.11) In this study, Cu (referred to as FPC-Cu hereinafter) and Al (FPC-Al) dies were used and the effect of the difference in the die material on the mechanical properties of the obtained porous Al was investigated. In addition, the mechanical properties of the obtained porous Al were compared with those of other porous Al samples fabricated by the SDP route, in which the sintering of the mixture is conducted by SPS.6­8)