The effect of annealing on the microstructure and tensile properties of a beta/gamma ' Ni-Al-Fe alloy

The evolution of the microstructure of a (beta/gamma') Ni-32 at.% Al-5 at.% Fe alloy during annealing has been studied by electron microscopy and X-ra y diffraction. Annealing at 800 degrees C and 1100 degrees C causes a rever se martensitic transformation, L1(0) --> B2 (beta), and a B2 --> L1(2) (gam ma') phase transformation. The lower annealing temperature leads to a highe r volume fraction of the gamma'-phase but a smaller size of the gamma'-part icles. The kinetic laws of the coarsening and of the increase in the Volume fraction of the gamma'-phase an discussed. The orientation relationships b etween the beta and gamma' phases appeared to be mainly of Nishiyama-Wasser mann and Bain types after 800 degrees C annealing, while Kurdjumov-Sachs an d Bain orientation relationships were predominant in the alloys annealed at 1100 degrees C. A strong correlation between the volume fraction of the ga mma'-phase and the tensile characteristics of the alloy has been establishe d. (C) 2000 Elsevier Science Ltd. All rights reserved.