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Affiliation of Author(s):材料科学与技术学院

Journal:Int. J. Heat Mass Transf.

Abstract:The initial planar instability will appear with the solute accumulation ahead of the solid/liquid (S/L) interface during solidification in a molten pool. The instability process is dominated by the misorientation angle and the surface tension anisotropy strength, where the misorientation angle is the angle between the preferred crystalline orientation of base metal and the thermal gradient direction in front of the S/L interface. In this study, their effects on the initial planar instability during gas tungsten arc welding of an Al-alloy are investigated using a modified analytic model and a quantitative phase-field model, respectively. Specifically, we apply the uniform fluctuation spectrum assumption, Aω(0) = kBTM/{γ0[1 − 15γ4cos(4θ0)]ω2}, to represent the influence of thermal noise on S/L interface evolution. The incubation time, average wavelength and detailed interface morphology of the initial planar instability are investigated with varying surface tension anisotropies (determined by anisotropy strength γ4 and misorientation angle θ0). The results indicate that -γ4cos(4θ0) is a reasonable indicator for the effect of surface tension anisotropy on the initial planar instability. Moreover, rather than influencing solute diffusion, the surface tension anisotropy just affects the planar interface stability during the solidification. Finally, the experimental observations with the same welding parameters was carried out, which are in general agreement with the simulated results. © 2018 Elsevier Ltd

ISSN No.:0017-9310

Translation or Not:no

Date of Publication:2019-03-01

Co-author:Yu, Fengyi,Ji, Yanzhou,Chen, Long-Qing

Correspondence Author:Wei Yanhong