Abstract
Oxide eutectic ceramic in situ composites prepared by directional solidification from the melt in the Al 2O 3–Ln 2O 3 systems are promising candidates for the manufacture of turbine blades because of their excellent mechanical properties. With high temperature gradient and rapid cooling rate, directionally solidified (DS) Al 2O 3/GdAlO 3(GAP) eutectic ceramics having smooth surface and full density are successfully prepared by laser zone remelting at the scanning rate of 240–720 mm/h. The microstructure development and solidification behaviour under rapid growth rate are investigated. Fine typical DS irregular eutectic structure of “Chinese script” consisting of interpenetrating α-Al 2O 3 and GAP phases is obtained at the scanning rate below 360 mm/h. Further increasing the scanning rate, the as-solidified Al 2O 3/GAP eutectic presents a combination of “Chinese script” and elongated colony microstructure with complex regular structure. Inside the colonies, the rod-type or lamellar-type eutectic microstructures with ultra-fine GAP surrounded by the Al 2O 3 matrix are observed. The interphase spacing is strongly dependent on the laser scanning rate, rapidly decreasing to the sub-micron range for the samples grown at the highest rate. Moreover, the formation condition and solidification mechanism of the particular microstructure of the ceramic composite during rapid solidification are discussed.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
