Microstructure and tensile properties of dual structure superalloys at intermediate temperatures

摘要

The microstructure and tensile properties of dual structure superalloys were investigated. Dual structure superalloys are directionally solidified into fine grains and columnar grains with aid of seeds technique. In the transition zone coarse grains and pseudo columnar grains are observed. MC carbides evolve from blocky to script-like and volume fraction of micro-pores decreases during transition from fine grains to columnar grains. The ultimate tensile strength of dual structure superalloys is slightly lower than that of the base superalloys with only fine grains or columnar grains in the present experiment, but reduction of ductility of the dual structure superalloys is not observed. The deformation and fracture behaviors of dual structure superalloys are analyzed based on the grain rotation and surface deformation morphologies.