J. Mater. Sci. Technol. ›› 2022, Vol. 130: 1-11.DOI: 10.1016/j.jmst.2022.03.038

• Research Article •     Next Articles

Alloy solidification: Assessment and improvement of an easy-to-apply model

H. Liua,*(), Y. Liua, S.L. Lub, Y. Zhanga, H. Chenc, Y. Chenb, M. Qianb,*()   

  1. aSchool of Materials Science and Engineering, Southwest Jiaotong University, Chengdu 610031, China
    bCentre for Additive Manufacturing, School of Engineering, RMIT University, Melbourne, VIC 3000, Australia
    cSchool of Materials Science and Engineering, Sichuan University, Chengdu 610065, China
  • Received:2021-12-19 Revised:2022-03-15 Accepted:2022-03-16 Published:2022-12-10 Online:2022-12-07
  • Contact: H. Liu,M. Qian
  • About author:E-mail addresses:ma.qian@rmit.edu.au (M. Qian)
    ∗ E-mail addresses:lhm@home.swjtu.edu.cn (H. Liu),

Abstract:

It has been a central task of solidification research to predict solute microsegregation. Apart from the Lever rule and the Scheil-Gulliver equation, which concern two extreme cases, a long list of microsegregation models has been proposed. However, the use of these models often requires essential experimental input information, e.g., the secondary dendrite arm spacing (λ), cooling rate ($\dot{T}$) or actual solidification range (ΔT). This requirement disables these models for alloy solidification with no measured values for λ, $\dot{T}$ and ΔT. Furthermore, not all of these required experimental data are easily obtainable. It is therefore highly desirable to have an easy-to-apply predictive model that is independent of experimental input, akin to the Lever rule or Scheil-Gulliver model. Gong, Chen, and co-workers have recently proposed such a model, referred to as the Gong-Chen model, by averaging the solid fractions (fs) of the Lever rule and Scheil-Gulliver model as the actual solid fraction. We provide a systematic assessment of this model versus established solidification microsegregation models and address a latent deficiency of the model, i.e., it allows the Lever rule solid fraction fs to be greater than one (fs > 1). It is shown that the Gong-Chen model can serve as a generic model for alloy solidification until fs reaches about 0.9, beyond which (fs > 0.9) its applicability is dictated by both the equilibrium solute partition coefficient (k) and the solute diffusion coefficient in the solid (Ds), which has been tabulated in detail.

Key words: Solidification, Microsegregation, Solute, Back diffusion, Eutectic formation