Synthesis and thermal reaction of stainless steel nanowires

Due to the perfection of microelectronics fabrication, silicon is presently the preferred base material in the design of micromechanical devices. By contrast, steels are the dominating construction materials in macroscopic engineering. So, it is appealing to explore the potential of stainless steel nano objects. To this aim, we developed an electrochemical method for and investigated the fabrication of FeCr(C) nanowires and study their thermal reaction to design the microstructure. Wires, 50 to 150 nm in diameter, are produced by template-assisted electro-deposition. Under thermal annealing, they develop first a core-shell structure of an Fe-rich core and a dense Cr-rich carbide shell. The shell thickness is well controllable via the initial composition of the wires. In a later, second reaction stage, wires with rather thin shells (about 8 nm thickness) demonstrate a 'stacking inversion' that finally leads in a self-driven reaction to the formation of hollow carbide tubes decorated with iron rich clusters on their outer surface.