Effects of processing conditions of a ball-milled Fe-Co-Nb-B alloy on the microstructural and thermal properties

The nanocrystalline Fe 56 Co 14 Nb 6 B 24 alloy was produced by high-energy ball milling. Structural, microstructural, and thermal properties of the milled powders were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), and differential scanning calorimetry (DSC). Microstructural parameters, including crystallite size, lattice strain, and lattice parameter, were determined from XRD data using Rietveld refinement. body-centered cubic (BCC) Fe-rich solid solutions constitute the primary crystallographic phase, while metastable boride phases of the Fe₂₃B₆, Fe₃B, and Fe₂B types, together with a minor Nb(B) phase, are also detected. The average crystallite size decreases to approximately 10 nm with prolonged milling, accompanied by increased microstrain and defect density. DSC analysis provides qualitative insight into structural relaxation, glass transition, and crystallization behavior associated with amorphous and nanocrystalline phase evolution, indicating excellent thermal stability of the milled alloy.