Influence of RE-rich phase distribution in initial alloy on anisotropy of HDDR powders**Project supported by the National Natural Science Foundation of China (Grant No. 51101167), the Ningbo Natural Science Foundation, China (Grant No. 2013A610075), the Ningbo Science and Technology Project, China (Grant No. 2013B10004), the Program of International Science and Technology Cooperation of China (Grant No. 2010DFB53770), the China Postdoctoral

Abstract

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.