Improved thermodynamic models for predicting thermophysical properties during very rapid solidification
To fill the data gaps, CALPHAD-based tools can be used to simulate these highly non-equilibrium processes and aid in the design of new alloys suited to additive manufacturing.
Specifically, CALPHAD tools can be used to calculate the following as a function of material chemistry and temperature:
- Thermophysical properties such as heat capacity, enthalpy, and density under non-equilibrium conditions arising from rapid cooling for input into FEA codes
- Microsegregation during solidification
- Precipitate evolution and growth during heating and cooling cycles
- Selecting temperatures for optimal post-build heat treatments
Coupled with FEA codes, these can be used to predict localized material properties by linking chemistry and processing conditions to microstructure. This talk highlights a few such Integrated Computational Materials Engineering (ICME) approaches. In one, the Scheil Gulliver equation was used to generate composition and temperature dependent data for latent heat and heat capacity, leading to improvements in the accuracy of finite element simulations to predict the size, shape, and temperature of the laser melt pool in 316L. Additionally, solute trapping models by Aziz and Kaplan are incorporated into the Scheil methodology, which takes into account the effect of very rapid solidification. A case study is presented to show how this can lead to better microstructure prediction in Alloy 718 and the effect of solute trapping on thermophysical properties to improve finite element modeling.
See more of: Materials 4.0: Materials Information in the Product Life Cycle