Analysis of the formation of FeAl with a high open porosity during electric current-assisted sintering of loosely packed Fe-Al powder mixtures

A Fe-40 at.%Al loosely packed powder mixture was subjected to pressureless treatment in a vacuum chamber of a Spark Plasma Sintering facility and sintered in a hot press in an argon atmosphere with and without applying mechanical pressure. The treatment conditions were varied to determine whether the electric current and the heating rate play any roles in the formation of FeAl compacts with a high open porosity (41-51%). Rapid heating of a loosely packed Fe-Al mixture in the SPS chamber with or without an electric current passing directly through the sample ensures a fast transformation of the reaction mixture into a highly porous FeAl product, the passage of electric current through the sample not being responsible for the preservation of high open porosities. The transverse rupture strength of porous FeAl did not depend on the sintering method for compacts of the same total porosity, but increased when the total porosity decreased.