Microscopic phase-field simulation of the coarsening behavior of coherent precipitates in Ni-Al alloys

Yanli Lu1), Zheng Chen1,2), Yongxin Wang1), and Yongsheng Li1) 1) School of Materials Science and Engineering, Northwestern Polytechnical University, Xi’an 710072, China 2) State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi’an 710072, China

摘 要：On the basis of the microscopic phase-field dynamic model and the microelasticity theory, the characteristics of the coarsening behavior of γ′ phase in Ni-Al alloys have been systematically studied in a certain volume fraction of the precipitates. It was found that the initial irregular shape, randomly distributed γ′ phase, gradually transformed into cuboidal shape, regularly aligned along the [100] and [010] directions, and a highly preferential selected microstructure was formed during the later stage of precipita-tion. The volume fraction of the precipitates produced some effects on the precipitate morphology but did not produce an obvious ef-fect on the regularities of precipitate distribution. The coarsening rate constant from the cubic growth law decreased as a function of volume fraction for small volume fractions, remained constant for intermediate volume fractions, and increased as a function of volume fraction for large volume fractions. During the coherent coarsening process, four "splitting" patterns between γ′ phases, which belonged to different antiphase domains, were produced via particle aggregation, such as an L-shaped pattern, a doublet, a triplet, and a quartet.

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