# Finite Interface Dissipation Phase Field Modeling of Ni-Nb under Additive Manufacturing Conditions

## TL;DR

This paper develops a computational framework coupling finite element thermal modeling with phase field modeling to predict microstructure evolution in Ni-Nb alloys during laser powder bed fusion additive manufacturing, capturing complex microsegregation and morphology variations.

## Contribution

It introduces a novel coupled modeling approach to simulate rapid solidification microstructures in Ni-Nb alloys under additive manufacturing conditions.

## Key findings

- Predicted cellular segregation morphology matches experimental data.
- Transition from planar to cellular interfaces depending on process mode.
- Microstructure features vary with temperature gradient and growth rate.

## Abstract

During the laser powder bed fusion (L-PBF) process, the built part undergoes multiple rapid heating-cooling cycles, leading to complex microstructures with nonuniform properties. In the present work, a computational framework, which weakly couples a finite element thermal model to a non-equilibrium PF model was developed to investigate the rapid solidification microstructure of a Ni-Nb alloy during L-PBF. The framework is utilized to predict the spatial variation of the morphology and size of cellular segregation structure as well as the microsegregation in single-track melt pool microstructures obtained under different process conditions. A solidification map demonstrating the variation of microstructural features as a function of the temperature gradient and growth rate is presented. A planar to cellular transition is predicted in the majority of keyhole mode melt pools, while a planar interface is predominant in conduction mode melt pools. The predicted morphology and size of the cellular segregation structure agrees well with experimental measurements.