Experimental Verification and Application of Computational Thermodynamic, Kinetic, and Solidification Modeling to Gas Atomized Al Powder

Abstract

In the majority of powder consolidation techniques, powder properties are disregarded due to particle melting during processing. In the solid-state cold spray process, however, powder particles significantly affect the mechanical properties of the consolidated material. Therefore, it is essential to fully characterize the powder properties in order to better predict properties of the cold sprayed deposit. An additive strength model is used to predict the powder particles' strength and hardness as a function of diameter. It is based on thermodynamic, kinetic, and solidification principles and considers contributions to the overall particle strength by solid solution strengthening, microstructural feature size, and precipitation/dispersion strengthening. This additive model quantifies the first two stages of the cold spray through-process model (TPM). The stages of the TPM are Powder Production, Powder Preparation, Cold Spray Parameters, Particle Impact, and Post-Processing. This paper focuses on the modeling and experimental works on the Powder Production stage of the TPM, in particular the strength contribution from microstructural feature size. For as-received gas atomized Al 6061 powder the increase to the intrinsic strength of the material due to the particles' microstructural feature size is between 60% and 40% for 10 um to 55 um particles, respectively. This paper compares theoretical predictions with experimental findings for the purpose of verification.