Phase formation in mechanically alloyed powders for potential magnetocaloric applications

Ball milling techniques have been used extensively in the last 30 years for the synthesis and processing of novel materials. The continuous fracturing and cold welding processes during milling allows to mechanically mix elements/compounds at an atomic scale, extend the solid solubility of metals and, in turn, obtain new alloys that might show interesting functional properties. In this contribution, we explored the possibility of using ball milling at different operating conditions to produce Mn-based or Ge-based alloys with attractive magnetocaloric properties. Ball milling was performed either at room temperature in argon, at liquid nitrogen temperature (cryomilling) or in a reactive hydrogen atmosphere. The as-milled powders were characterized by powder X-ray diffraction and differential scanning calorimetry. The effect of substitution of Mn for other 3d transition elements or substitution of Ge for other p-block elements is investigated with respect to the phase selection process during ball milling.