Effect of heat treatment on the microstructure and mechanical properties of 7075 aluminum alloy cold-spray coatings

Abstract

Cold Spray (CS) exhibit unique features due to the low temperatures involved. However, the CS coating are harder than the corresponding powders and bulk alloys, which results in a low toughness and then greatly limits the application of CS. To overcome this shortage, preheat treatment of powder and post-heat treatment of CS coating are applied to improve the performance of cold-sprayed 7075 aluminum alloy coatings in this work. With increasing temperatures of post-heat treatment, the tensile strength of the coatings increased from 228 MPa to 309 MPa with elongation of 2.46%. Microstructure analysis of the heat-treated coatings revealed that the improvement in mechanical properties was primarily due to an increase in the secondary phase. Accordingly, 7075 aluminum alloy powder was preheat treated at 200 °C and then used for cold spraying, which resulted in improved mechanical properties in the resultant coatings exhibiting a tensile strength of 302 MPa and an elongation of 3.87%. These findings provide valuable insights into the practical application of cold-spraying technology in the aviation field.