Title :
Effect of Ambient Aging on Heat-Treated Mechanically Alloyed Mn-Al-C Powders
Author :
Obi, Ogheneyunume ; Burns, Laird ; Yajie Chen ; Bennett, Sheila ; Sawicki, Marek ; Kaplan, David ; Arango, Ana M. ; Lewis, Laura H. ; Harris, Vincent G.
Author_Institution :
Dept. of Electr. & Comput. Eng., Northeastern Univ., Boston, MA, USA
Abstract :
The effect of ambient aging upon the magnetic and structural properties of heat-treated mechanically alloyed Mn0.53Al0.47-xCx powders was systematically investigated. Their properties were examined after 6, 15, 21 and 52 weeks of aging. XRD data revealed no detectable structural changes in the carbon-doped alloys. With x = 0.01 and 0.015, the magnetic properties were stable up to 52 weeks with only a slight variation of ~7%-10%. Conversely, with x = 0, magnetic property variations greater than 30% were demonstrated. This confirms that carbon doping of the MnAl alloys not only improves the stability of the τ phase during heat-treatment but also over a prolonged period of time. Curie temperature (TC) of the alloys was determined using the first derivative of the differential scanning calorimetry (DSC) data. Only 1% decrease in TC was observed for the aged heat-treated alloy with x =0.01 compared to that for the pre-aged alloy.
Keywords :
Curie temperature; X-ray diffraction; ageing; aluminium alloys; carbon; differential scanning calorimetry; doping; magnetisation; manganese alloys; powder metallurgy; powders; Curie temperature; DSC; Mn0.53Al0.47-xCx; XRD; ambient aging; carbon doping; differential scanning calorimetry; heat treatment; magnetic properties; magnetisation; mechanically alloyed powders; structural properties; time 6 week to 52 week; Aging; Carbon; Magnetic properties; Magnetosphere; Manganese; Powders; Ambient aging; Mn-Al-C alloys; magnetization; mechanical alloying; permanent magnets;
Journal_Title :
Magnetics, IEEE Transactions on
DOI :
10.1109/TMAG.2013.2243709
