Aging characteristics of thermomechanically processed Cu-9Ni-6Sn alloy

Citation
Ss. Kim et al., Aging characteristics of thermomechanically processed Cu-9Ni-6Sn alloy, SCR MATER, 40(1), 1998, pp. 1-6
Citations number
6
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Apllied Physucs/Condensed Matter/Materiales Science",Metallurgy
Journal title
SCRIPTA MATERIALIA
ISSN journal
1359-6462 → ACNP
Volume
40
Issue
1
Year of publication
1998
Pages
1 - 6
Database
ISI
SICI code
1359-6462(199812)40:1<1:ACOTPC>2.0.ZU;2-E
Abstract
Cu-Ni-Sn alloys have gathered a considerable amount of interests over the p ast 20 years, since the strength level of Cu-Ni-Sn alloys with a proper the rmomechanical processing equals to those obtained by high-strength, precipi tation-hardened Cu-Be alloys (1-3). The aging response of Cu-Ni-Sn alloys i s known to be extremely sensitive to aging temperature, aging time and prio r processing history (1-4). When Cu-Ni-Sn alloys are aged below 400 degrees C after solution heat treatment, for example, the supersaturated solid sol ution ct is reported to follow the three stages of decomposition. In the fi rst stage, the modulated structure with Sn-rich and Sn-poor regions forms a long the [100]alpha direction as a result of spinodal decomposition. In the second stage, the metastable gamma' precipitates with D0(22) type structur e nucleate from the modulated structure, and the highest strength occurs in this stage. In the final stage of transformation, the gamma' phases decomp ose into the cellular structures, consisted of equilibrium a and gamma phas es, and the strength ceases to increase. The effect of cold working prior t o aging practice on tensile properties of Cu-Ni-Sn alloys is significant, b ut still controversial (1,2,5). In the present study, aging characteristics of heavily swaged Cu-9Ni-6Sn al loy, the composition of which is known to have the best combination of mech anical and physical properties, were examined. The hardening behaviors of C u-9Ni-6Sn alloys, either solutionized and aged or directly aged, are discus sed with SEM fractographic studies and TEM micrographic observations.