Carbon as a sacrificial alloying element in processing Fe-P soft magnetic alloys

摘要

The present investigation deals with designing Fe-P based binary alloy produced by in-house developed powder metallurgical technique based on ‘Hot Powder Preform Forging’. Proper soaking of preforms at high temperature (1050°C) eliminates iron-phosphide eutectic and brings entire phosphorus into solution in iron. Attempting hot forging thereafter completely eliminates hot as well as cold shortness and thereby helps to form these preforms into very thin sheets of 0.5mm. The use of costly hydrogen atmosphere during sintering has been eliminated by use of addition of carbon. The glassy ceramic coating applied over the compact serves as a protective coating to avoid atmospheric oxygen attack over the compact held at high temperature. The alloy so formed was subjected to density examination at various stages. Microstructural study has been carried out to estimate the grain size, volume percentage porosity in the alloy and uniform distribution of phosphorus in iron matrix. Fe-0.07wt% C-0.3wt% P alloy so formed yielded coercivity as low as 0.45 Oe, resistivity as high as 17.4 μΩcm and total loss as low as 0.176 W/Kg. The alloy which is drawn to thin sheets could find its possible application in manufacturing transformer cores.