Mechanical & Materials Engineering, Department of


Date of this Version

Summer 2012


A THESIS Presented to the Faculty of The Graduate College at the University of Nebraska In Partial Fulfillment of Requirements For The Degree of Master of Science, Major: Mechanical Engineering, Under the Supervision of Jeffrey E. Shield. Lincoln, Nebraska: May, 2011

Copyright (c) 2012 Santanu Mukherjee


Nanocomposite permanent magnets have recently evoked wide interest because of their interesting properties. They usually consist of a hard magnetic phase having superior coercivities and a soft magnetic phase having improved values of magnetization and when they are coupled together, we get a permanent magnet with enhanced values of both the parameters and thus can be put to a lot of applications. Also to make this possible we can take advantage of the principle of exchange interaction which has been discussed subsequently in detail.

Also the microstructure plays a major role in obtaining good magnetic properties and the microstructure is usually controlled by the cooling rates i.e. the wheel speeds during the melt spinning process as well as heat treatment process i.e. annealing. Both these experimental techniques have been used to study the variation of magnetic properties of Nd12Fe82B6 and Nd10Fe84B6 which were formed using different wheel speeds. They were also annealed to study the changes in their magnetic properties. Mechanical milling was employed to improve the coercivities of the as cast system.

The next project was to build a non-rare earth permanent magnet using MnIr-Fe. Mechanical milling and subsequent annealing was used to study the changes in phase and the subsequent improvement in magnetic properties. The principle behind this was the exchange coupling of the antiferromagnetic MnIr alloy with the soft ferromagnetic Iron.

Advisor: Jeffrey E. Shield