1975 Volume 61 Issue 10 Pages 2456-2466
Microscopic observations have been made on a 1% Cu-3% Ni-1% Al steel in the solution-treated and aged state in order to make clear the mechanism of aging induced by simultaneous addition of Cu, Ni, and Al.
The extraction replica, transmission electon microscopic and electron diffraction studies have shown that precipitation of ε phase occurs in the initial stage of aging, and subsequently, B2 type super lattice intermetallic compound α′ phase (NiAl) precipitates preferentially at grain boundaries and with the progress of aging it precipitates in matrix. Identification and analysis of dispersed precipitates by EPMA have shown that Ni is enriched into dispersed precipitates with progress of aging.
On the basis of these results, aging mechanism of the steel has been discussed.