Microstructural and thermal investigations of iron–silicon nanocomposite materials synthesised by rod milling

Abstract

Based on X-ray diffraction (XRD) investigations and thermal analysis assisted by differential scanning calorimetry (DSC), the far from equilibrium phase transitions induced by conventional or modified horizontal rod mills, when starting from a mixture of Fe and Si elementary powders 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 curves reveal that the rod milled end products are nanocomposite materials formed by a mixture of a disordered nanocrystalline A2 phase, an amorphous phase and some traces of non-reacted Si powders. It has been concluded that for both the crystalline to amorphous phase transition and the Si atom dissolution in the A2 solid solution, the rod milling becomes more effective when the cylinder rotation speed approaches an optimal value and when using an adequate number of rods (i.e. when using 170 rpm cylinder rotation speed and two rods). A partial crystallisation of the amorphous phase and a partial precipitation of the dissolved Si atoms are observed to occur for higher injected shock power values (i.e. when using 3 rods and 170 rpm cylinder rotation speed).