High pressure gas-solid interstitial modification with H and N atoms and HDDR processing of Nd(Fe,M)(12) (M=Ti,V,Mo)

The pressure dependency of hydrogenation and nitrogenation in the range of 1-30 bar and the hydrogenation disproportionation desorption recombination (HDDR) process in NdFe11Ti, NdFe10.75V1.25 and NdFe10.5Mo1.5 were studied b y differential scanning calorimetry, differential thermal analysis, tempera ture-pressure analysis, x-ray diffraction, and high resolution scanning ele ctron microscopy. With increasing gas pressure from 1 bar to 30 bar the tem peratures of interstitial absorption and decomposition reactions decrease b y typically 30 K, During the decomposition reaction with nitrogen the phase NdFe10.5Mo1.5, like the other two phases, transforms into alpha-Fe;and an amorphous phase. At a pressure of 1 bar the hydrogen disproportionation rea ction occurs at 713 degrees C, 670 degrees C and 815 degrees C for NdFe11Ti , NdFe10.75V1.25 and NdFe10.5Mo1.5, respectively, The HDDR process was succ essfully performed for all compounds.