Platinum Metals Rev., 1957, 1, (4), 135
Platinum Alloy Permanent Magnets
The Director of Research of the Permanent Magnet Association, Mr. J. E. Gould, has written to point out that Columax, which has been in production in this country for some years, has a higher value of (BH) max (7 to 8 × 106) than any of the commercial permanent magnet materials quoted in the table accompanying the article on “Platinum Alloy Permanent Magnets” in our last issue. It thus can be said to provide permanent magnets as powerful as those which can be made from cobalt-platinum alloys.
Columax is the name given to Alcomax magnets which have been cast (by special foundry technique) in such a way that columnar crystals are developed oriented in the preferred axis of magnetisation.
It is fair to emphasise that the coercive force of cobalt-platinum permanent magnets, 4000 oersteds, is well above that of Columax (840 oersteds) and that the cobalt-platinum alloys, unlike any of the cast materials, are ductile before hardening and so can be readily fabricated.