Contribution to the Study of the Structural, Microstructural and Magnetic Properties of Nanostructured Fe (100− X ) Mg X Alloys Prepared by Mechanical Alloying

ABSTRACT Nanocrystalline powders of Fe (100− x ) Mg . x alloy were synthesised by a mechanical alloying process, via a high‐performance planetary milling, using a Retsch PM400 planetary mill. This study explored phase synthesis and examined the physical properties of these alloys by varying the magnesium content, x , for values of 5, 10, 15, 20, 33 and 45 wt. %. To characterise these materials, a range of analytical techniques, including X‐ray diffraction (XRD), scanning electron microscopy (SEM), energy‐dispersive X‐ray analysis, transmission electron microscopy (TEM), laser diffraction granulometry and magnetic measurements via a vibrating sample magnetometer, were employed. Furthermore, the apparent density of the alloys was determined using Archimedes' method, revealing a significant reduction in density with increasing magnesium content, thereby confirming the lightweighting effect of the Fe–Mg system. A complete transformation into a body‐centred cubic (bcc) α‐Fe(Mg) solid solution phase was detected in the Fe 95 Mg 5 sample after 24 h of milling. Increasing magnesium concentration up to 15 wt. % caused an extension of the lattice parameter beyond 0.2880 ± 0.0001 nm, while the average crystallite size, expressed by 〈D〉 (in nm), significantly reduced. Additionally, the level of microdistortions, noted 〈ε〉 (in %), increased, revealing varied trends depending on the magnesium concentration for the bcc α‐Fe and hcp Mg phases. Observations from SEM, combined with laser granulometry analyses, indicated a direct correlation between magnesium concentration and particle morphology: low concentration led to finer particles, while high concentration favoured particle agglomeration and increased particle size. TEM microscopy validated these observations, confirming the presence of the α‐Fe phase in the Fe 95 Mg 5 alloy. Remarkably, the Fe 80 Mg 20 alloy exhibited a significant coercivity field of 220.7 ± 5 Oe, while maintaining relatively low values of remanence and saturation magnetisation at 29.53 ± 2 emu/g, thereby exhibiting the characteristics of a hybrid magnetic behaviour combining soft and semi‐hard magnetic characteristics.