Experimental Investigation Thermal and Mechanical Behavior of Ni/Al Reactive Composites Synthesized by Mechanical Alloying

Reactive composites are a new group of composite materials consisting of two or more metal materials that can not ignite or explode in the environment but can release a lot of energy due to shock and severe impact loads. This study aimed to investigate the effect of the ratio of constituent particles on the microstructure and thermal and mechanical properties of the Al-Ni composite. For this purpose, the Al-Ni compound with 2:1, 1:1 and 3:1 molar ratios was milled and mixed. Then the samples were cold pressed and sintered at 400 ˚C under argon atmosphere for one hour. The microstructure of samples was analyzed by microstructure field emission scanning electron microscopy (FESEM) and XRD. For the investigation of thermal and mechanical properties, DTA and ignition tests and compression and Hopkinson tests were used respectively. In the ignition test, due to the AlNi product, the highest value of heat released was related to a sample with 1:1 Al:Ni molar ratio. In the compression and Hopkinson tests, the highest values of compressive strength were 208.7 and 309.7 Mpa respectively, which belong to a 1:1 Al:Ni molar ratio. Also, the results showed that the compressive strength increased by changing the strain rate from 0.01 s-1 (in the pressure test) to 1000 s-1 (in the Hopkinson test).