Abstract
The tensile deformation and fracture behavior of directionally solidified superalloy DZ125L were studied with a strain rate ranging from 10−3 to 7 × 102 s−1 at room temperature. Results show that the strength of DZ125L alloy presents positive strain rate sensitivity in tested strain rate range which is mainly resulted from the increasing accumulation of dislocations in the matrix. The ductility of the alloy first increases and then it remains insensitive with the increase in strain rates. The enhancement of ductility is primarily due to the increasing amount of broken MC carbides and plastic deformation in the matrix at higher strain rates. The strain rates influence the amount of broken MC carbides and then affect the deformation behavior of the alloy. Based on observations and discussions of the lateral microstructures and dislocations, it is concluded that the MC carbides with sizes larger than 10 μm are easy broken in the early deformation stage and act as crack sources during the proceeding plastic deformation. The growth and connection of microcracks and the propagation of main crack lead to the fracture of the matrix.
Published Version
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