Nanocrystalline Al2O3-Ni(Cr) particle synthesis by high-energy mechanical alloying method

Nanostructured feedstock material results in better surface protective coatings under high-temperature oxidation erosion environment. This research paper focuses on synthesizing ceramic-metallic (cermet) nanostructured Al2O3-Ni(Cr) feedstock particles using high-energy mechanical alloying (HE-MA) powder processing technology. The underscoring particle design objectives were twofold: (1) reduce the ceramic oxide grain size below 20 nm, and more pressingly (2) embed nano-scaled grains inside metal/alloy binder particles, hence the nanostructured cermet particles. The novelty of this research work lies in the successful embedment of nanostructured Al2O3 grains into the micron sized Ni(Cr) metallic binder matrix. In a SPEX mill with a milling speed of 1200 rpm along with variation in milling time following two separate material design compositions (design of experiments) it was possible to meet the stated objectives. Results show good conformance between the experimental and analytical data in terms of obtaining Al2O3 grain reinforced Ni(Cr) nanostructured particles with mean grain and particle sizes standing at 19 ± 1.15 nm and 15 μm ± 4.6 μm, respectively, after 12 h of milling.