“…This is specifically important if a nanopowder matrix is reinforced with nanoparticles, nanotubes, and nanosheets to prepare a hybrid nanocomposite powder. Methods, such as simple wet dispersion and probe sonication [35,36], ball milling [24,32,37,38,39,40,41], molecular level mixing [21,26,42,43], sol-gel processing [44,45,46,47], and colloidal processing [22,23,35,48,49] were used to improve the dispersion of the reinforcements in alumina matrix.…”