TEMPERATURE DEPENDENCE OF VICKERS HARDNESS OF R-Fe AND La-Fe-Al AMORPHOUS ALLOYS

Temperature dependence of Vickers hardness of several kinds of R-Fe ( R : rare earth metal ) and La-Fe-Al amorphous alloys has been investigated. The decrement of Vickers hardness below the Curie temperature is steeper than that in the paramagnetic temperature range, owing to their large spontaneous volume magnetostriction. The curves exhibit a peak due to the crystallization, except for La-Fe amorphous alloys. Because La-Fe alloy system makes no alloys and compounds, its hardness is decreased drastically by crystallization. However, by addition of Al to La-Fe alloys, the temperature dependence is similar to that of other R-Fe alloy systems, accompanying the increase in the magnitude of hardness. No distinct softening due to the glass transition has been observed in the present amorphous alloys. In R-Fe amorphous alloys, the magnitude of hardness in the paramagnetic temperature range exhibits a systematic change in connection with the lanthanide contraction