Inconel 718/Al2O3 nanocomposite powders produced by sonication-assisted high-energy ball milling (HEBM) and mechanofusion processes are presented and compared. Powders were pre-mixed via sonication in ethanol. Two pre-mixed batches were processed by HEBM using two different cooling temperatures and milling times. To investigate the influence of Al2O3 on the mechanical milling stages, Inconel 718 powder without alumina was also mechanically milled. Results show that the tested methods are able to produce Inconel 718/Al2O3 composite with suitable characteristics for further manufacturing or functionalization. A homogeneous dispersion of nanosized alumina throughout the metal matrix was only achieved by milling, showing a monomodal particle size distribution, with controlled both morphology and composition. Low cooling milling temperatures reduce Inconel 718/Al2O3 composite production time using less mechanical energy during milling. Sonication-assisted HEBM is an adequate method for the fabrication of non-commercial nanocomposites to be used as raw material in different manufacturing techniques.