Low temperature coefficient cobalt-rare earth magnets

Co-Gd-Sm alloys were made by calcium co-reduction of mixtures of Gd
2
O
3
and Sm
2
O
3
in the presence of cobalt powder. Both the base alloy (Co
5
Gd
0.4
Sm
0.6
) and the sintering additive (Co
7
Gd
0.8
Sm
1.2
) were made by this lower cost R/D process. Die-pressed magnets with a reversible temperature coefficient of magnetization of -0.004 %/°C and an energy product of 9.9 MGOe were made. These magnets performed well in a TWT stack. Co-Ho and Co-Er alloys were also made by the calcium reduction of their oxides. And, one Co-Ho-Sm magnet made from ingot material had a
(BH)_{\max}= 12.4
MGOe and a reversible coefficient equal to zero near room temperature.