Surface modification of ultrafine YAl₂ intermetallics particles by mix milling

The dispersibility of large particle reinforcement in the composites was improved by mix milling. The mix milling for ultrafine YAl₂ particles with different Mg particles was further investigated. The morphology, phase composition and microhardness of different Mg particles were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and microhardness tester. The parameters such as milling rotation speed and ball milling time on the modification effect were studied by SEM and energy spectrum analysis (EDS). The results showed that industrial magnesium powder had a higher thickness with a similar oval shape; magnesium chips (under sawing) had a lower thickness with an angular shape; magnesium chips (under drilling) had a higher thickness with many special microstructure like gusset on the surface. The different Mg particles had close microhardness. And the equivalent diameters of industrial magnesium powder, magnesium chips (under sawing) and magnesium chips (under drilling) were 70, 350, 1700 μm, with corresponding ratios of thickness to diameter(H/D)of 0.14, 0.03, 0.06~0.12, respectively. The surface modification effect of ultrafine YAl₂ particles was reduced as magnesium chips (under sawing), industrial magnesium powder, magnesium chips (under drilling), which was related to the different ratios of thickness to diameter. The ultrafine YAl₂ particles were coated by Mg films when mix milled with magnesium chips (under sawing) for 2 h with a 150 r·min^-1 milling rotation speed, and the dispersion of ultrafine YAl₂ particle was improved.