STRUCTURAL, MECHANICAL AND MAGNETIC-PROPERTIES IN HEAT-TREATED -LESS-THAN-OR-EQUAL-TO-X-LESS-THAN-OR-EQUAL-TO-12) ALLOY RIBBONS

The evolution of structural (X-ray, Mossbauer spectroscopy), mechanica l (Young's modulus, Delta E effect) and magnetic (hysteresis loops) pr operties of Fe73.5Si22.5-x BxNb3Cu1 (6 less than or equal to x less th an or equal to 12) alloy ribbons is followed after heating at increasi ng temperatures, T-a, up to full devitrification of the amorphous prec ursors into a nanocrystalline state. Overall modifications in structur e correlate with magnetic and mechanical characteristics, which are an alyzed through the induced changes in parameters as internal stress an d magnetostriction. Relaxation of amorphous structure (T-a approximate to 440 degrees C) results in magnetic softening and increase of Delta E effect. First stages of crystallization (T-a approximate to 480 deg rees C), including a Cu clustering, induces a relative magnetic harden ing and reduction of Delta E effect. Optimum nanocrystalline state (T- a 540 degrees C) with the softest magnetic behavior leads to a final i ncrease of Young's modulus. The influence of relative weights of Si an d B is also analyzed. (C) 1997 Acta Metallurgica Inc.