Abstract: The microstructure and microsegregation of atomized powder, which depend on their sizes, are of great importance to the mechanical properties of the consolidated bulk materials. Therefore, it is necessary to reveal the relationship between particle size and powder attributes. The effects of particle size on the solidification characterization of the atomized Ni-based superalloy powders were studied via finite element simulation. Based on the simulations, a model was developed to predict the microsegregation and microstructure of atomized powders with different sizes and study the influence of thermal history on the powder attributes during the atomization processes. The radiation heat transfer and temperature gradient within the rapid solidification alloy powders were taken into account in this model. For validating the accuracy of the model, the predictions of the present model were compared with the microsegregation and microstructure of the specific size powder close to the screen mesh size. The results showed that microstructure depended primarily on the temperature gradient within the powder, while the solidification rate had a more significant effect on the microsegregation. The model predicted microstructure features in agreement with the experiment, and for microsegregation, the deviations of prediction for most elements were less than 10%. This work provides a new model to precisely predict the microsegregation and microstructure of the atomized alloy powders and sets a foundation to control the powder features for various engineering applications.

Key words: Particle size, Solidification microstructure, Microsegregation, Numerical simulation