Dynamic Compaction Of Amorphous Ni78P22

The changes ocuring in the structure of dynamically compacted amorphous Ni78P22 powder in the pressure range 50–150 kbar were studied. Powder was compacted by shock waves obtained during explosion of high explosives. At 50 kbar Ni78P22 does not crystallize, but increases in pressure cause both crystallization, which is completed at 150 kbar, and the formation of stable crystalline Ni and Ni3P phases. The minimum porosity was obtained at 70 kbar. The mechanism of hydrogen sorption seems to be the same on dynamically compacted samples as well as on the initial amorphous powder. Any shift of crystallization temperature of the amorphous phase remaining after dynamic compaction was not detected, but the activation energy for crystallization was somewhat lower (— 150 kJ/mol) than the value corresponding to the crystallization of unshocked amorphous powder (212 kJ/mol). These data may indicate that shock waves cause a certain “destabilization” of amorphous Ni78P22.