Phase field modeling of solidification in multi-component alloys with a case study on the Inconel 718 alloy
- PDF / 585,507 Bytes
- 11 Pages / 584.957 x 782.986 pts Page_size
- 39 Downloads / 154 Views
ank Querfurth Teconsult Precision Robotics, Bayreuth 95448, Bavaria, Germany, and Materials and Process Simulation, University of Bayreuth, Bayreuth 95447, Bavaria, Germany
Uwe Glatzel Metals and Alloys, University of Bayreuth, Bayreuth 95447, Bavaria, Germany (Received 14 June 2017; accepted 7 September 2017)
We develop a phase field model for the simulation of chemical diffusion-limited solidification in complex metallic alloys. The required thermodynamic and kinetic input information is obtained from CALPHAD calculations using the commercial software-package ThermoCalc. Within the case study on the nickel-base superalloy Inconel 718, we perform simulations of solidification with the explicit consideration of 6 different chemical elements. The stationary dendritic tip velocities as functions of the constant undercooling temperature obtained from isothermal solidification are compared with the stationary tip temperatures as functions of the imposed pulling velocity obtained during directional solidification. We obtain a good quantitative agreement between the two different velocity—undercooling functions. This indicates that the model provides a self consistent description of the solidification. Finally, the simulation results are discussed in light of experimental solidification conditions found in single crystalline casting experiments of Inconel 718.
I. INTRODUCTION
Understanding solidification is the key to many aspects of the microstructure of nickel base superalloys, and is thus also directly or indirectly related to the resulting mechanical properties of this important class of materials.1 In recent years, progress has also been made in addressing technologically relevant aspects of microstructure formation during solidification using computer simulations within the emerging field of integrated computational materials engineering. Certainly, this would not be possible without the strong basis of dendritic growth theory. Since the fundamental discovery of a steady state solution to the problem of diffusion-limited solidification in the free space by Ivantsov,2 it took quite a long time to finally understand that the interfacial energy, and in particular its anisotropy, both play a central role in dendritic growth3,4: In the classical case, it is the anisotropy of the interfacial energy which determines the growth direction, the dendritic tip-radius as well as the growth velocity all together within the so-called dendritic selection. However, apart from the rather weak interface energy anisotropy, other anisotropic physical Contributing Editor: Mathias Göken a) Address all correspondence to this author. e-mail: michael.fl[email protected] DOI: 10.1557/jmr.2017.393
effects can also provide such a selection of stationary diffusion-limited growth patterns in the free space.5 In the special case of a purely isotropic interfacial energy and no further anisotropic physical effect present in the system, stationary dendritic-type solutions do not even exist and instead unsteady see-weed or directionally unstable doublon stru
Data Loading...
