Development of porous ceramic layers through sublimation of metal phases in multiphase alloys

Here described is a procedure for the fabrication of porous ceramic layers onto metallic substrates. Porous ceramic layers with submicron sized pores can readily develop by taking advantage of eutectic solidification and sublimation of a metallic phase upon high temperature exposure. The material in the present study is based on the Ir–Y system, where two-phase microstructures comprised of Ir and Ir3Y are formed through solidification process. A eutectic solidification yields submicron-scaled Ir particles within the Ir3Y matrix. Upon air-exposure at 1373 K, the Ir phase forms volatile oxides and the Ir3Y phase transforms into Y2Ir2O7, by which porous ceramic layers develop on the surface of the base materials.