Sintering temperature dependence of microstructure evolution and compression performance of a novel circular Al honeycomb fabricated via powder sintering

Abstract

In this study, a novel circular Al honeycomb with hierarchical porous size was fabricated by powder sintering at different temperatures (400–600 °C), utilizing an Al/Mg powder mixture as metallurgical bonding layers between hollow Al tube arrays. It aimed to investigate the effect of sintering temperature on the phase evolution, the metallurgical bonding at the powder-tube interfaces, and the diffusion behavior of Mg in the inner and outer walls of the tubes in the honeycombs. The results indicated that Al₃Mg₂ and Al₁₂Mg₁₇ phases formed in the powder layers at 400 °C, while only the Al(Mg) solid solution phase was present above 450 °C. As the temperature increased, the diffusion depth of Mg in the inner and outer walls of the tubes increased, which broadened the bidirectional Mg concentration gradient and corresponding bidirectional microhardness structure. This resulted in higher Mg content and enhanced microhardness at the center of the tube walls. Meanwhile, the rise in temperature enhanced the metallurgical bonding both within the powder layers and between the powders and the tube walls, leading to improved compressive performance of the honeycombs. The honeycomb sintered at 600 °C, in general, exhibited the optimal mechanical properties, with a plateau stress of 63.2 MPa. This study clearly elucidated the strengthening mechanism of metallurgical bonding at the powder-tube interfaces and the diffusion behavior of Mg in both the inner and outer walls of the Al tubes at various sintering temperatures, which offered significant theoretical insights for the preparation and performance optimization of circular Al honeycombs.