Investigation of strengthening mechanism in Ni-38Cr-3.8Al alloy with fine lamellar structure by in situ neutron diffraction analysis

Koyanagi, Yoshihiko*; Ueta, Shigeki*; Kawasaki, Takuro   ; Harjo, S.   ; Cho, K.*; Yasuda, Hiroyuki*

The strengthening mechanism of Ni-38Cr-3.8Al (mass%) alloy with fine lamellar structure composed of the and -Cr layers, which is formed by discontinuous precipitation, was examined by in situ neutron diffraction analysis. The contribution of each constituent phase on the deformation behavior could be separated by the in situ analysis. The plastic deformation occurred preferentially in the and phases, while the -Cr phase deformed more elastically even beyond the yield point of the and phases, which is similar to the cementite in pearlite of a steel. Fine nano-lamellar structure formed by the discontinuous precipitation is found to be mainly responsible for high strength of the alloys, while the influence of the precipitates on strength is likely to be small.