Influence of CuO addition on the microstructure, exothermic characteristics and mechanical properties of Al/Ni/CuO energetic structural materials prepared by friction stir additive manufacturing

In order to fabricate energetic structural materials (ESMs) possessing high energy density and mechanical properties, bulk Al/Ni/CuO ESMs were prepared by friction stir additive manufacturing (FSAM). The microstructure, exothermic characteristics, and mechanical properties of Al/Ni/CuO ESMs with varying CuO content were investigated systematically. The microstructure morphologies were analyzed by field emission scanning electron microscope, X-ray diffraction and transmission electron microscope. Exothermic characteristics were carried out by differential scanning calorimetry. The compression experiments and the microhardness tests were applied to evaluate mechanical properties. The results showed that the compressive strength elevated from 261 MPa to 394 MPa, the average microhardness increased from 118 HV to 134 HV and the exothermic energy density rose from 498 J/g to 665 J/g as the CuO content of additive manufactured Al/Ni/CuO ESMs increased from 0 to 15 wt.%. Compared to the Al/Ni ESM, the additive manufactured Al/Ni/CuO ESM with 15 wt.% CuO exhibited excellent mechanical properties and energy density. The friction stir treatment generated numerous Al 3 Ni nanoparticles and improved distribution of agglomerated CuO particles in the FSAM zone. The initial reaction temperature of ESMs rose obviously as the addition of CuO particles, because there were many CuO particles in the Al/Ni interfaces, which hindered the diffusion reaction between Al and Ni. The enhancements in mechanical strength were primarily due to dislocation strengthening, second phase strengthening of Al 3 Ni particles and CuO particles.