Effects of Process Parameters on Cold Spray Additive Manufacturing of Quasicrystalline Al93Fe3Cr2Ti2 Alloy

Abstract

Quasicrystalline Al93Fe3Cr2Ti2 (at.%) gas-atomized powders, which exhibit a metastable composite microstructure, were used to produce coatings by cold spray additive manufacturing processing (CSAM) using different processing parameters. The metastable composite microstructure provides the Al93Fe3Cr2Ti2 alloy with excellent mechanical properties. At the same time, the metastability of its microstructure, achieved by the high cooling rates of the gas atomization process, limits the processability of the Al93Fe3Cr2Ti2 powder. The purpose of this study was to investigate the effect of process parameters on the CSAM of quasicrystalline Al93Fe3Cr2Ti2 powder. The powder was sieved and classified to a size range of −75 µm. Using N2 carrier gas combined with different temperatures, pressures, nozzle apertures, and deposition substrate conditions, cold-sprayed coatings were produced. The porosity and thickness of the coatings were evaluated by image analyses. By SEM, XRD, DSC, and TEM, the microstructure was identified, and by Vickers microhardness, the mechanical properties of the coatings were investigated. Dense (≤0.50% porosity) and thick (~185.0 µm) coatings were obtained when the highest pressure (4.8 MPa), highest temperature (475 °C), and lowest nozzle aperture (A) were used in combination with an unblasted substrate. The SEM, XRD, and DSC data showed that the composite powder’s microstructure was retained in all coatings with no decomposition of the metastable i-phase into equilibrium crystalline phases. Supporting these microstructural results, all coatings presented a high and similar hardness of about 267 ± 8 HV. This study suggests that the CSAM process could, therefore. produce metastable quasicrystalline Al93Fe3Cr2Ti2 coatings with a composite microstructure and high hardness.