Investigation of Microstructure and Mechanical Properties of Ni-Al Energetic Structural Materials Prepared by Cold Spraying

Ni-Al energetic structural materials (ESMs) have been a popular choice for various defense applications due to their excellent mechanical performance. However, the relationship between stagnation temperature and microstructural and mechanical properties of Ni-Al ESMs prepared by cold spraying remains unclear. In this study, three different Ni-Al ESM samples were prepared by cold spraying at stagnation temperatures of 300 °C, 350 °C, and 400 °C. The microstructural characteristics were analyzed using an x-ray diffractometer (XRD), scanning electron microscope, and transmission electron microscope, revealing the presence of stacking faults and a large number of dislocations near the grain boundaries in the Ni phase area. In addition, stress concentration was observed near the grain boundaries. Quasi–static compression tests were also conducted to analyze the mechanical properties. The results showed that the compressive strengths of the Ni-Al ESM samples were 198 MPa, 199 MPa, and 204 MPa with a stagnation temperature of 300 °C, 350 °C, and 400 °C, respectively, and the fracture strains were 0.24, 0.22 and > 0.6, respectively. Based on these findings, the stagnation temperature has little effect on the compressive yield strength of the Ni-Al ESMs prepared by CS, but it significantly increases the fracture strain.