MICROSTRUCTURAL AND THERMAL INVESTIGATIONS OF IRON-SILICON NANOCOMPOSITE MATERIALS SYNTHESIZED BY ROD MILLING

Based on X-ray diffraction (XRD) investigations and thermal analysis a ssisted by differential scanning calorimetry (DSC), the far from equil ibrium phase transitions induced by conventional or modified horizonta l rod mills, when starting from a mixture of Fe and Si elementary powd ers in, respectively, 81.9 and 18.1 atomic fractions (Fe+18.1 Si at.%) , were studied. The analyses of the XRD patterns as well as the DSC cu rves reveal that the rod milled end products are nanocomposite materia ls formed by a mixture of a disordered nanocrystalline A2 phase, an am orphous phase and some traces of non-reacted Si powders. It has been c oncluded that for both the crystalline to amorphous phase transition a nd the Si atom dissolution in the A2 solid solution, the rod milling b ecomes more effective when the cylinder rotation speed approaches an o ptimal value and when using an adequate number of rods (i.e. when usin g 170 rpm cylinder rotation speed and two rods). A partial crystallisa tion of the amorphous phase and a partial precipitation of the dissolv ed Si atoms are observed to occur for higher injected shock power valu es (i.e. when using 3 rods and 170 rpm cylinder rotation speed). (C) 1 998 Elsevier Science S.A.