CHEMICALLY PREPARED FE-B ULTRAFINE AMORPHOUS ALLOY PARTICLES - INFLUENCE OF THE REACTION-TIME ON THE PROPERTIES

Fe-B ultrafine amorphous alloys have been prepared by adding the solution of potassium borohydride into the solution of ferrous sulfate. The reaction process, monitored by the change in pH value during the reaction, and the effect of addition rate of KBH4 solution, i.e., the reaction time, were investigated. It was found that the reaction system automatically maintains its pH value at about 4.6 and the molar ratio of KBH4 to FeSO4 for the equivalent reaction is 1.9. The boron content increased with the time used for adding 142 ml of KBH4 solution up to about 50 min and then decreased. Generally, the particle size was smaller for high addition rate (e.g. 590 Å with 7 sec) and large for low addition rate (e.g. 1370 Å with 96 min). The amorphous structure of the Fe-B alloys was also found to be different with different reaction time used. © 1993 Academic Press, Inc.