Microstructure of Fe-based ODS high-temperature alloy sheet prepared by EBPVD

Large-sized Fe-based ODS (Oxide Dispersive Strengthen) high-temperature alloy sheets were successfully synthesized by EBPVD (Electron Beam Physical Vapor Deposition) technique. The sheets were about 120pm thick, and having a diameter of 1000mm, whose surface roughness was less than 1μm (Ra<1μm). The microstructures were examined by SEM (Scanning Electron Microscope). The grain size was 1-4μm. When the substrate temperature was 600°C, the sheet had sharp irregular polyhedral grain, and when the substrate temperature was 700°C the sheet had quite regular grains. The morphological orientation angle increased with the distance from the center of the sheet. During the first period of deposition, the sheet was growing in a G-L-S mode, which corresponded with the corn-like microstructure in the cross-section. While during the final period, the sheet changed into a G-S growing mode, which corresponded to the smooth columnar microstructure.