Cyclic-loading microstructure-property relations from a mesoscale perspective: An example of single crystal Nickel-based superalloys

JOURNAL OF ALLOYS AND COMPOUNDS

卷:770

Article

Wu, Ronghai^1,2  Zaiser, Michael^2,3 

[1] Northwestern Polytech Univ, Sch Mech Civil Engn & Architecture, Xian 710129, Shaanxi, Peoples R China

[2] Friedrich Alexander Univ Erlangen Nurnberg, Dept Mat Sci, WW8 Mat Simulat, Dr Mack Str 77, D-90762 Furth, Germany

[3] Southwest Jiaotong Univ, Sch Mech & Engn, Chengdu, Sichuan, Peoples R China

关键词: Superalloy;    Cyclic loading;    Phase-field;    Continuum dislocation dynamics;    Mesoscale simulation;   

DOI  :  10.1016/j.jallcom.2018.08.168

来源: Elsevier

【 摘 要 】

Past models of stress-strain response under cyclic loading mainly rely on macroscopic equations which consider microstructure evolution indirectly or simply discard microstructure information. Modern materials science, on the other hand, seeks quantitative descriptions for the relations between microstructure and loading response. In the present work, we show a promising mesoscale phase-field framework which can describe co-evolution of phase/grain and defect microstructures, reveal microstructure mechanisms and simultaneously predict deformation properties as a natural outcome of microstrucuture interactions. The energy functionals for phase/grain and defect microstructures are constructed, followed by functional variation which leads to governing equations. Applying the developed framework to high temperature cyclic loading of single crystal Nickel-based superalloys, the simulated results show that cyclic loading-microstructure-property relations can be principally revealed. In the short term perspective (in one cycle), dislocations move back and forth, leading to cyclic loops consistent with characteristics observed in experiments. The plastic strains are one order of magnitude smaller than total strains, which explains why the cyclic loops are very thin. In the long term perspective, all gamma/gamma' microstructures exhibit directional coarsening similar to creep under zero cyclic loading ratio, with the extent of rafting slightly dependents on cyclic waveform, period, etc. The plastic strains are sensitive to cyclic loading conditions both in terms of curve shape and in terms of magnitude. (C) 2018 Elsevier B.V. All rights reserved.

【 授权许可】

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