A hybrid approach to improve microstructure and mechanical properties of cold spray additively manufactured A380 aluminum composites

This study comprehensively determined the microstructure and mechanical properties of cold spray additively manufactured A380 alloy components. In this regard, three types of Al2O3/A380 composite deposits were prepared by separately mixing spherical, irregular, and spherical + irregular shaped Al2O3 particulates with the original A380 alloy powder. The as-sprayed deposits were subsequently subjected to heat-treatment at 350 degrees C for 4 h. The effects of Al2O3 morphology on the microstructure and mechanical properties of A380 deposits were systematically investigated at different processing stages by electron backscattered diffraction analysis and tensile testing, respectively. Moreover, the evolution of defects (pores and dislocation) inside the deposits was comprehensively studied using X-ray computed tomography and transmission electron microscopy techniques. The results indicated that the deposit containing spherical Al2O3 exhibited significantly reduced porosity, grain refinement and a significant increase in strength (similar to 70%) in contrast to the pure A380 alloy deposit. This could be attributed to the tamping effect of the spherical Al2O3 particles. In contrast, the irregular Al2O3 particles primarily indicated the embedding effect with recurrence of fragmentation events inside the deposit. Consequently, the deposit containing irregular Al2O3 indicated only a slight decrease in porosity and a 40% increase in strength in contrast to the pure A380 alloy deposit. The tensile test results indicated that heat-treatment significantly improved the plasticity of deposits through fusion of nano-sized pores, reduction in dislocation density and static re-crystallization. Therefore, the hybrid approach of adding a suitable tamping aid to the original A380 alloy powder and post-spray heat-treatment optimized the microstructure of cold spray additively manufactured components to significantly improve their mechanical properties.