(Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China)
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DOI:
10.7502/j.issn.1674-3962.2012.12.01
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Abstract:
Single crystal superalloys have been widely used to make turbine blades and guide vanes for aeroengines and industrial gas turbines because of improved strength, creeprupture, fatigue, oxidation and hot corrosion properties as well as stable microstructure and reliability at high temperature environments. After removal of grain boundary by using directional solidification technique, grain boundary elements that decrease the incipient melting temperature were reduced remarkably in single crystal superalloys. Consequently, the solution and aging treatment of single crystal superalloys can be done at higher temperature due to the enhanced incipient melting temperature, and then the high temperature strength of single crystal superalloys is higher than that of equiaxed and directionally solidified superalloys. There were great progresses on approach of alloy design, relationship between structure and mechanical performances, process of pure smelting and directional solidification in the last decades. The present work reviews these progresses from compositions of alloys, role of elements, mechanism of strengthening, anisotropy of mechanical properties, procedure of solidification, control of defects and processing of single crystal superalloys.