The aim of these investigations is a
better understanding of the way in which
materials based on NdFeB and SmFe react with
hydrogen and nitrogen at elevated temperatures.
Hydrogen is the basis of both the
hydrogen-decrepitation (HD) and
(HDDR) processes, however, the reactions between
the NdFeB-based materials and hydrogen are far
from being thoroughly understood. The HDDR
process is also used with SmFe-based materials,
where it is able to reduce the grain size and
homogenise the material and make it suitable for
Our studies have concentrated on the effects of
substitutions such as Zr, Dy, and Pr (for NdFeB
materials) and Ta (for SmFe materials) on the
HDDR reaction. We have made use of the fact that
disproportionation produces iron as a reaction
product to develop a magnetic monitoring system
based on a vibrating-sample magnetometer (VSM).
The system can operate in the temperature range
from 12 K to 1300 K, and in any atmosphere from a
vacuum to 1.2 bar overpressure.