Effect of Growth Rate on Microstructure and Mechanical Properties of ftie Directionally Solidified Nb-Si Eutectic Alloy

摘要

The development of ultra-high temperature structural materials having superior mechanical properties to the nickel based superalloys has been pursued in the niobium silicide based composites. The unidirectional solidification technique was performed on the (Nb)/Nb_3Si eutectic alloy in the Nb-Si binary system. A continuity of Nb phases in the eutectic microstructure increases with decreasing a growth rate, which yields the enhancement of fracture toughness as well as high temperature strength. The mechanisms of microstructural formation, toughening, and strengthening are briefly discussed.