Author:
Mukhtarov S K,Ganeev A A,Shakhov R V,Imayev V M,Logunov A V
Abstract
Abstract
Superplastic behaviour of a polycrystalline nickel-base superalloy Ni-47(Cr,Co,W,Al,Ta,Hf)-0.2(C,B) (wt.%) in the fine-grained condition obtained via thermomechanical treatment (TMT) has been studied. TMT transformed a coarse-grained as-cast structure into a homogeneous fine-grained one. Both the initial as-cast and the thermomechanically treated conditions contained not only the matrix γ phase, the hardening γ’ phase and carbides but also topologically close-packed (TCP) phases. In spite of the presence of the TCP phases, the superalloy in the fine-grained condition demonstrated superplastic properties (δ>300% and low flow stresses) at subsolvus temperatures. Superplastic deformation led to some refinement and alignment of the TCP phase particles along the tensile axis.