Abstract: The high-temperature tensile fracture behavior of the Ni, Cr, AI-TaC eutectic superalloy directionally solidified under high temperature gradient is investigated. The hightemperature tensile fracture of this in situ composite has ductile character with lots of ductile nests whose diameters decrease with the increasing solidification, rates. The maximum δb and δ are respectively 668.5MPa and 19.6％. There is a TaC whisker in the center of each nest, and the deformation of γ' and TaC is uneven. The hightemperature tensile behavior cannot be explained by the rule of mixtures but is decided by the formation of the plastic deformation band. The crack extension model is given.

Key words: Ni, Cr, Al-TaC eutectic superalloy