In situ observation of liquid metal dealloying and etching of porous FeCr by X-ray tomography and X-ray diffraction

Abstract A liquid metal dealloying mechanism is investigated in situ using X-ray tomography and X-ray diffraction. While immersing a FeCrNi precursor alloy in a molten Mg bath, a selective dissolution of Ni atoms into the Mg bath occurs leading to FeCr atom rearrangement. At room temperature, after cooling down, a bicontinuous structure of FeCr and a solid solution of Ni in Mg is obtained. A final etching step is used to remove the Mg solid-state solution phase and form microporous FeCr. 3D dealloying and etching kinetics can be measured using X-ray tomography reconstruction. The evolution of relative strain is analyzed from X-ray diffraction patterns. The different behavior observed during dealloying and etching, depending on the precursor composition is discussed.