Vol 7, No 3 (2016) > Metalurgy and Material Engineering >

Effects of Water Quenching Before Hydrogenation, Disproportionation, Desorption and Recombination Process on Magnetic Properties of Nd-Fe-B Powder

Sri Bimo Pratomo, Yongjin Kim, Djoko Hadi Prajitno

 

Abstract:

In general, the Nd-Fe-B
as-cast ingot is homogenized for a long time before the hydrogenation, disproportionation, desorption and
recombination (HDDR) process, to produce good magnetic properties. Since the homogenizing process is expensive, this work examined the
possibility of replacing it with
a water quenching process for
Nd-Fe-B magnetic powder. The magnetic powders were soaked at 1100oC for 4 hours,
followed by water quenching prior to HDDR. The
resulting powder had magnetic properties
that were almost
similar to magnetic powder that was homogenized prior to HDDR. The remanence values of the water-quenched
alloy and the homogenized
alloy were 7.8 KG and 8.9 KG, respectively, while the coercivity values were
12.6 KOe and 10.3
KOe, respectively. In general, the magnetic properties of both samples were not much
different. The microstructure of Nd2Fe14B phase combined
with a very
slight Nd rich phase in micro grain boundary likely caused the coercivity enhancement.

Keywords: Coercivity; Homogeneizing; HDDR; Water quenching

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