Porous Metals with Enhanced Mechanical and Magnetic Properties by Ultra-Fast High Temperature Sintering

Porous metals are attractive engineering materials due to their high gas/liquid permeability, high strength-to-weight ratio, low density, and excellent energy absorption. Among the various fabrication methods, powder metallurgy stands out as a promising approach for fabricating porous metals with a well-defined network of interconnected pores. However, conventional furnace sintering is time-consuming and energy-inefficient. In addition, the inherent porosity of these materials compromises their mechanical strength and facilitates rapid crack growth. Thus, researchers have developed structural porous materials such as sandwich composites and bamboo-like gradient porous structures to enhance the mechanical properties of porous materials. Despite these advances, efficient fabrication methods for complex structural materials remain lacking. In this work, porous metals with strong mechanical properties are fabricated by ultra-fast high temperature sintering (UHS) of iron powders. UHS achieves high temperature sintering in less than 30 seconds, resulting in strongly connected porous structures. The short sintering time leads to small grain sizes, which further enhance the mechanical properties. Moreover, we have successfully fabricated sandwich or bamboo-like structural porous metals with robust interlayer connections using a one-step UHS process. Mechanical testing of UHS samples reveals significantly higher flexural strength and modulus compared to furnace-sintered samples with equivalent porosity. Furthermore, the porous iron metals demonstrate low magnetic core loss at high frequencies due to their small grain sizes and high porosity, highlighting their potential for practical applications in electrical machines, inductors, and transformers.