화학공학소재연구정보센터
Materials Science Forum, Vol.357-3, 417-422, 2001
Low temperature and high strain rate superplasticity of nickel base alloys
This paper will describe features of micro-, submicro-, and nano-crystalline structure formation under severe plastic deformation and the influence of structure on superplastic (SP) behavior of high alloyed nickel base alloys with a range of hardened precipitates (gamma'; gamma "+delta, gamma'+Y2O3). It has been shown that severe plastic deformation over a wide range of homologous temperatures (0.9-0.2T(m)) can refine the microstructure to a size of several tens of nanometers. In comparison with the microcrystalline (MC) state, the submicrocrystalline (SMC) structure in dispersion hardened alloys reduces the optimal temperature of SP deformation from 0.9-0.8T(m) to 0.7-0.6T(m). The PDS alloy combines precipitation and dispersion hardening (gamma'+Y2O3), and, in the SMC state, it can display both low temperature and high strain rate superplasticity. Features of microstructure transformations and failure of samples during SP deformation are considered.