Phase transition in a Cu-14.1A1-9.0Ni alloy

Abstract

The phase transition of the Cu-14.1 wt.% Al-9.0 wt.% Ni alloy has been examined by transmission electron microscopy and energy-dispersive X-ray analysis. In the as-quenched condition, the microstructure of the alloy was Do(3) phase that contained extremely fine L-J precipitates. During the early stage of isothermal aging at 500 degreesC, a high density of the extremely fine B2 particles was observed within the extremely thin lamellar gamma(1)' martensite, which was formed by a D0(3) --> gamma(1)' martensitic transformation during quenching. With increasing aging time at 500 degreesC, the isothermal phase transition sequence was found to be D0(3) --> D0(3) --> B2 --> D0(3) + B2 + alpha --> B2 + alpha + gamma(2). This transition significantly differs from that observed by other researchers. Besides, both Kurdjumov-Sachs (K-S) and Nishiyama-Wassermann (N-W) orientation relationships between the B2 particle and the alpha phase could be detected in the aged alloy. (C) 2003 Elsevier Science B.V. All rights reserved.