Influence of RE-rich phase distribution in initial alloy on anisotropy of HDDR powders

The influence of the RE-rich phase distribution in the precursor alloys on the anisotropy of the hydrogenation disproportionation desorption recombination (HDDR) processed powders is investigated. The homogenized ingot alloy and the as-cast strip casting (SC) alloy with a uniform RE-rich grain boundary phase lead to high anisotropy of the refined powders, acquiring degrees of alignment (DOA) of 0.62 and 0.54, respectively. The RE-rich phase aggregation results in a deteriorated DOA of the powders due to the drastic disproportionation rate, while a thin and uniform RE-rich phase distribution is beneficial for DOA. A reaction model of the initial particle microstructure is proposed for optimizing the HDDR powder anisotropy.