The Effect of Temperature on the Magnetic Properties of the Electrochemically Obtained Ni_92.8 Mo_7.2 Powder Pressed at Different Pressures

Abstract

The Ni92.8Mo7.2 alloy powder was obtained by electrochemical codeposition from an ammonium solution of NiSO4 and (NH4)6 Mo7O24 at j = 100 mA m-2, on a titanium cathode. DSC measurements and determination of the dependence of electrical resistivity on temperature did not reveal any changes in powder structure in the temperature range from 293 to 460 K. Therefore, in this range, there was no significant change in magnetic susceptibility either. Structural relaxation took place in the temperature interval from 460 to 560 K causing an increase in magnetic susceptibility. At temperatures higher than 570 K, magnetic susceptibility rapidly decreased. The Curie temperature of the powder was 660 K. With the increasing powder pressing pressure the magnetic susceptibility increased while the electric resistivity decreased. With the pressing pressure increase, the pore size was decreased and a better contact between powder particles was established. This caused electrical resistivity decrease and magnetic susceptibility increase.