Title :
Phases and magnetic properties of mechanically milled Pr-Fe-B-X alloys during heat treatment
Author :
Lee, D.G. ; Kim, D.Y. ; Jeung, W.Y. ; Kang, I.K.
Author_Institution :
Div. of Metals, Korea Inst. of Sci. & Technol., Seoul, South Korea
fDate :
9/1/1992 12:00:00 AM
Abstract :
Microcrystalline Pr-Fe-B powders with high coercivity have been prepared by mechanically milling the as-cast ingot and a subsequent heat treatment. The mechanism responsible for the high coercivity is discussed with the results obtained using an X-ray diffractometer, vibrating sample magnetometer, a DC fluxmeter, a different thermal analyzer, and a transmission electron microscope. The mechanical milling process causes the refinement of Pr2Fe14B, α-Fe, and Pr-rich phases through a process of continuous fracture and cold welding. During heat treatment a new metastable phase and a layered Pr2Fe14B phase are formed at about 420°C and 480°C, respectively. The thickness of the multilayer is about 0.1 μm. This structure provides the milled powder with the high coercivity of 13-18 kOe after the heat treatment. The addition of Ge to Pr-Fe-B alloy improves the squareness and maximum magnetic energy product of the mechanically milled alloys
Keywords :
X-ray diffraction examination of materials; boron alloys; coercive force; crystal microstructure; ferromagnetic properties of substances; germanium alloys; heat treatment; iron alloys; permanent magnets; powder metallurgy; praseodymium alloys; thermal analysis; transmission electron microscope examination of materials; DC fluxmeter; Pr15Fe79B5Ge1; X-ray diffractometer; cold welding; continuous fracture; different thermal analyzer; heat treatment; high coercivity; layered Pr2Fe14B phase; magnetic properties; maximum magnetic energy product; mechanical milling; metastable phase; microcrystalline Pr-Fe-B powders; phase refinement; squareness; transmission electron microscope; vibrating sample magnetometer; Coercive force; Germanium alloys; Heat treatment; Iron; Magnetic analysis; Magnetic properties; Magnetometers; Milling; Powders; X-ray diffraction;
Journal_Title :
Magnetics, IEEE Transactions on
