Cold-Spray Processing of a High Density Nanocrystalline Aluminum Alloy 2009 Coating Using a Mixture of As-Atomized and As-Cryomilled Powders

Abstract

In this work, a mixture of as-atomized and as-cryomilled powders instead of the pure as-cryomilled powder was used as feedstock to achieve high density nanocrystalline coatings by cold spraying. Cryomilled powder with nanocrystalline grains was produced by mechanical milling under liquid nitrogen and the grain size range was from 5 to 30 nm. A mixture of 30 wt.% as-atomized powder and 70 wt.% as-cryomilled powder was sprayed onto the aluminum substrates. High density coatings were attained by use of this kind of mixture, which was described as an effective method to decrease porosity in the cold-sprayed nanocrystalline coating. The functions of the as-atomized powder in the coating were discussed. The mechanical behavior of the powders and the coating were studied using nanoindentation technique.