The effect of B<inf>4</inf>C addition on pore morphology of the ALSI7 foams

Abstract

In this study, the effect of B4C addition on pore morphology of the AlSi7 foams produced via powder metallurgy method was examined. For this, 7 % Si, 1 % TiH2 (foaming agent) and B4C powders at various rates (2, 4 and 6 %) were added to the Al powders and then mixed properly. Mixed powders were compacted at 400 MPa and extruded and rolled to produce precursor material. Then produced samples were freely foamed at temperatures between 690 °C and 750 °C in order to produce closed cell metallic foams. As a result of experimental studies, the volumetric expansion rate of B4C reinforced preform materials has been found to be lower than AlSi7 foams. Expansion values was found to be increase with increasing the foaming temperature. The maximum volumetric expansion values (350 % - 400 %) in nearly all samples was obtained at 750 °C foaming temperature. Pore size and sphericity factor were increased with foaming temperature and the amount of B4C in the samples but they reduced the number of pores.