Preparation and surface modification of submicron YAl₂ particles by mixed milling with magnesium for fabricating YAl_2p/MgLiAl composites

A new process for the preparation and surface modification of submicron YAl₂ intermetallic particles was proposed to control the agglomeration of ultrafine YAl₂ particles and interface in the fabrication of YAl_2p/MgLiAl composites. The morphological and structural evolution during mechanical milling of YAl₂ powders (<30μm) with magnesium particles (~100μm) has been characterized by scanning electron microscopy, transmission electron microscopy, and X-ray diffraction. The results show that YAl₂ particles are refined to submicron scale and separately cladded in magnesium coatings after mixed milling with magnesium particles for 20h. Mechanical and metallurgical bonds have been found in YAl₂/Mg interfaces without any interface reactions. Both the refining and mechanical activation efficiencies for YAl₂ particles are enhanced, which may be related to the addition of magnesium particles leading to atomic solid solution and playing a role as "dispersion stabilizer".