The present invention provides a supermagnetostrictive alloy capable of
providing a larger shift (lager magnetostriction) with excellent
workability, which is applicable to an actuator in response to advances in
downsizing of electronic devices and upgrading of medical instruments and
production apparatuses. The supermagnetostrictive alloy has a degree of
order of 0.6 to 0.95 achieved by subjecting Fe.sub.3-x Pt.sub.1+x
(-0.02.ltoreq..times..ltoreq.0.2) to a heat treatment. The present
invention also provides a method for the preparation of a
supermagnetostrictive alloy having a magnetostriction of 0.3% or more,
particularly 0.5% or more, comprising the steps of subjecting the
Fe.sub.3-x Pt.sub.1+x alloy of a raw material to a homogenization
annealing, and then subjecting the resulting product to a heat treatment
at 700 to 1000 K for 0.5 to 600 hours.
