The best single use of the
lanthanoids is for the production of alloy steels for plates and pipes A
well known alloy is mischmetall which consists of a lanthanoid metal
(~ 95%) and iron (~ 5%) and traces of S, C, Ca and Al A good deal of
mischmetall is used in Mg-based alloy to produce bullets, shell and
lighter flint Mixed oxides of lanthanoids are employed as catalysts in
petroleum cracking