Mechanically Driven Alloying and Magnetic Properties in Immiscible Mn<sub>80</sub>Bi<sub>20</sub> Nanocrystalline Powders

Abstract

The paper has described the formation of nanocrystalline Mn80Bi20 powders by mechanical alloying and studied the changes of structure and magnetic properties of the powders during the process of ball milling by using X-ray diffraction and saturation magnetization σs measurements. The solid solubility of bismuth in manganese increases with milling time and tends to a stable value after 80h milling. The σs of Mn80Bi20 increases abruptly with milling time at the early stage and begins to decrease after 15h. At the time of 15h, the σs reaches a maximum, which is about 7Am2/kg. The result shows an interesting information that the antiferromagnetic Mn and the diamagnetic Bi produce ferromagnetic Mn80Bi20 in process of mechanical alloying.