Shock compression response of α-Fe16N2 nanoparticles

The shock compression response of alpha ''-Fe16N2 nanoparticles is studied in order to evaluate the thermo-mechanical stability of the alpha '' phase under shock loading. Shock compression experiments were performed using the parallel plate impact gas gun set up at velocities near 850 m/s. The experiments were performed at -21 degrees C and -126 degrees C in order to minimize temperature excursions and thereby determine the thermal effects on the phase stability. The alpha ''-Fe16N2 phase is observed to partially decompose into alpha-Fe and gamma'-Fe4N in both samples, as detected by the XRD analysis. The lower temperature produces a higher percentage of gamma' phase in addition to the gamma ''-Fe50N50 phase. The pressure-volume-temperature response of the material is modeled using the dynamic mechanical properties of high nitrogen steel. The model is then used to evaluate the temperature excursions and their effect on the phase transitions observed. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4704368]