Neutron diffraction analysis and solidification modeling of Impulse-Atomized Al-36 wt%Ni

Peritectic solidification reactions appear in many metallic systems such as Al-Ni alloys. However, microstructural evolution and effects of processing parameters on phase selection during peritectic reaction are not well understood. In this paper Impulse-Atomization experiments and simulations were used to study rapid solidification of Al-36 wt% Ni particles. Secondary dendrite arm spacing measurements were used to estimate the cooling rate achieved during the solidification of these particles. The weight fractions of the phases formed in different sizes of the particles were measured using neutron diffraction technique. Solidification paths were then simulated with a model previously validated for concurrent dendritic, peritectic and eutectic phase transformations in binary alloys. Model predictions are compared to the experimental results to understand the sequence of transformations that leads to the final metallurgical state of the particles.