Revealing the mechanisms of grain nucleation and formation during additive manufacturing

The Interdependence model is now widely used to analyze the results of grain refinement studies. Although the model was developed to predict the grain size of an alloy cast under the assumptions of near equilibrium solidification and the presence of potent nucleant particles, it has been found to be applicable to a wide variety of alloys, casting methods, and cooling conditions. However, the strength of the Interdependence model is when it is used as a diagnostic tool that can reveal the mechanisms influencing the refinement of alloys under particular solidification conditions. This paper presents an introduction to the Interdependence model, its recent validation by experiment, and examples of how it can be applied to the solidification of alloys during additive manufacturing. For example, the model explains the difficulties in promoting a transition from columnar to equiaxed grains during additive manufacturing while also providing insights into how a fully equiaxed grain structure can be achieved