New reinforcement methods are introduced for the large Barkhausen and Matteucci effects in amorphous magnetostrictive wires. Cold-drawn and then torsion annealed (CDTA) wires (Fe77.5Si7.5B15, 50 μm diameter) generate ac pulse voltages, e'p, (Matteucci voltage, for short) of 35∼75 mV between the two ends of 200-mm long wires for 2 Oe, 60 Hz external fields. The critical wire length, l*, for the large Barkhausen (LB) effect is about 25 mm, which is useful for construction of small sized field sensors. The critical field, H*, for LB effect is 0.3∼0.9 Oe. The value of e'p/l* of the CDTA wires is more than 200 times that of as-prepared 125μm diameter wires. Magnetoelastic wave propagation characteristics are also remarkably improved in the CDTA wires.
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Kawamura et al. (1988) studied this question.