Microstructure Evolution and Compressive Properties of Multilayered Al/Ni Energetic Structural Materials under Different Strain Rates

Abstract

Multilayered Al/Ni energetic structural materials integrating exothermic properties and mechanical properties were prepared by the method of electrodeposition and hot pressing in this research. Then, the uniaxial quasi-static compression and split Hopkinson pressure bar experiments were conducted at strain rates from 10−4 to 6.5 × 103 s−1 at room temperature. The effects of compression strain rate on the microstructure evolution and the compressive properties of multilayered Al/Ni energetic structural materials were systematically investigated. With increasing quasi-static compression strain rate, the compression strength increased slightly for two kinds of Al/Ni multilayers prepared under different hot pressing time. With the hot pressing process extending to 4 h, the dynamic compression strength of multilayered Al/Ni composites monotonically increased from 494.7 to 564.2 MPa with increasing strain rate. It was shown that Al/Ni energetic structural materials exhibited evident strain hardening and strain rate strengthening. However, when the compression strain rate reached 6500 s−1, the Al/Ni composite prepared with the hot pressing time of 1 h showed prominent thermal softening. Notwithstanding, it was found that the compression strength of Al/Ni composite prepared at 4 h was evidently higher than that at 1 h, since the second phase reinforcement counteracted the thermal softening. In addition, the critical failure strain presented obviously increasing tendency with the increased compression strain rates.