Spinodal decomposition, ordering transformation, and discontinuous precipitation in a Cu-15Ni-8Sn alloy
Spinodal decomposition, ordering transformation, and discontinuous precipitation in a Cu-15Ni-8Sn alloy
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DOI：
10.1016/s1359-6454(98)00095-0
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发表时间：
1998-07-24
期刊：
影响因子：
9.4
通讯作者：
Notis, MR
中科院分区：
文献类型：
--
作者：
Zhao, JC;Notis, MR
Transmission electron microscopy (TEM) was employed to study the microstructure and transformation kinetics of a Cu-15Ni-8Sn (wt%) alloy. Five different transformation products were observed. a modulated structure resulting From spinodal decomposition; a DO22 Ordered structure; an L1(2) ordered structure; grain boundary and intragranular gamma (DO3) precipitates; and discontinuous gamma precipitates. It was found that spinodal decomposition occurred during the early stage of decomposition below similar to 500 degrees C. DO22 ordering appeared after spinodal decomposition, and Lit ordering appeared after DO22 ordering. Discontinuous precipitation took place at a very late stage of the decomposition process. A time-temperature transformation (TTT) diagram was established on the basis of extensive TEM characterization. Five separate C-curves were found for the five transformation products. This TTT diagram is very helpful in clarifying the confusion and inconsistency in the literature concerning the precipitation process in the alloy. This work is one of the first experimental studies which report that spinodal decomposition can take place before ordering. It also provides evidence for the coexistence of both DO22 and L1(2) long range order (LRO) structures in the alloy. (C) 1998 Acta Metallurgica Inc. Published by Elsevier Science Ltd. All rights reserved.
