Combustion Synthesis Reaction Behavior of Cold-Rolled Ni/Al and Ti/Al Multilayers
Final rept. Jan 2006-Jan 2008
ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD WEAPONS AND MATERIALS RESEARCH DIRECTORATE
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A two- or three-stage combustion synthesis reaction process was observed in cold-rolled NiAl and TiAl multilayer foils. The phase evolution sequence from the two foil types was studied by differential scanning calorimetry DSC. Several exothermic peaks were identified from the DSC thermograms. Subsequently, the foils were heated to each peak temperature to identify the reaction product associated with each peak. X-ray diffraction and scanning electron microscopy analyses were used to further discern the thermal events, whether they corresponded to intermediate or final reaction products. The NiAl foils went through three reaction stages. In the first stage, Al3Ni was formed as the reaction product. During the second stage, the part of the foil underwent thermal explosion. In the last stage, the heat released by the thermal explosion triggered a self-propagating high temperature synthesis reaction that resulted in the formation of AlNi. In contrast, the TiAl foils experienced only two reaction stages. In the first, the reaction zone propagated across the foil with formation of Al3Ti at the TiAl interface. Then, a thermal explosion reaction occurred in the part of foil that was heated, resulting in many different phases.
- Inorganic Chemistry