Abstract

Cu-6wt.%Ni-3wt.%Al was solutionised at 1173 K, cold rolled to 50 % and aged at 773 K. Transmission electron microscopy indicates that ageing of this material results in an initial recovery of the deformed matrix followed by precipitation of β-NiAl and γ′ -Ni₃Al and recrystallization. The γ′ precipitates show a uniform distribution everywhere except zones near grain boundaries and shear bands which serve as preferential nucleation sites for β-NiAl precipitates. The recrystallization fronts were found to cause dissolution of γ′ precipitates but during further ageing a secondary precipitation of γ′ phase in recrystallized areas was observed. The highest strength, i. e. σ_m = 590 MPa, σ_0.2 = 520 MPa, was achieved after 6 · 10³ s of ageing.