Porous metal micro-pillars by thermomechanical molding of two-phase alloys

Abstract

Creep-based thermomechanical molding of crystalline metals has emerged as a low-cost manufacturing technique for metal nanostructures. Here, we demonstrate the potential of such molding approach in fabrication of porous metal microstructures by using binary alloys such as Au-Si and Al-Cu. Two-phase alloys were isothermally molded against microscale templates followed by selective etching of one of the phases resulting in porous micro-pillars. The porosity of micro-pillars was varied by changing the phase fractions through alloy composition. Scanning electron microscopy is used to understand the different stages of molding and etching processes for two-phase metal alloys. While the nanoscale thermomechanical molding of similar alloys has been attributed to diffusional creep, the microscale forming presented here is dominated by the dislocation and grain boundary mediated deformation mechanisms. The molding and selective etching methodology can be potentially used to tailor the size and the distribution of pores by optimizing the microstructure of feedstock alloy.