Magneto-elastically excitable tag having a reliable deactivatable amorphous alloy for use in a mechanical resonance monitoring system

In a tag having magneto-elastically excitable strip for use with a source of a pre-magnetization field, for activating said tag, and an alternating magnetic field in a mechanical resonance monitoring system, the improvement of said strip comprising an amorphous, magnetostrictive alloy having constituents satisfying the formula

• Fea COb Cob Nic Six By Mz
• wherein M denotes at least one element of groups IV through VII of the periodic table, including C, Ge and P, and the constituents in at % meet the following conditions:
• a lies between 20 and 74,
• b lies between 4 and 23,
• c lies between 5 and 50,
• b+c>14,
• x lies between 0 and 10,
• y lies between 10 and 20,
• z±5, and
• with x+y+z lies between 12 and 2 21;
• and
• said amorphous, magnetostrictive alloy having a resonant frequency associated therewith and when passed through an alternating magnetic field having an alternation frequency coinciding with said resonant frequency, said strip producing a pulse having a signal amplitude, and said amorphous, magnetostrictive alloy exhibiting a change in resonant frequency and signal amplitude due to a change in orientation of the tag in the earth's magnetic field which is smaller than less than 1 kHz and a change occurring in resonant frequency upon removal of the pre-magnetization field to deactivate said tag which is greater than 1 kHz, and a change in said signal amplitude due to said change in orientation of the tag in the earth's magnetic field which is smaller than a change upon removal of the pre-magnetization field to deactivate said tag, and said strip having a flat magnetization loop produced by a thermal treatment in a transverse magnetic field at a temperature in a range from 250° C. to through 450° C. for a duration of from 2 through 60 seconds.