Synthesizing of Nanostructured Fe-Mn Alloys by Mechanical Alloying Process
Authors/Creators
Description
Highlights of the Study
This study investigated the synthesis of nanostructured Fe–30 wt.% Mn alloy through high-energy mechanical alloying, focusing on the effects of milling time and ball-to-powder mass ratio on phase evolution, crystallite refinement, lattice strain, solid-solution formation, and particle morphology. Increasing both milling time and milling intensity promoted Fe–Mn solid-solution formation and nanostructural refinement, with the combination of 10 h milling and a ball-to-powder mass ratio of 30 producing a homogeneous nonmagnetic γ-Fe-based Fe–Mn solid solution with a crystallite size of approximately 6 nm.
Key findings:
🟢 Mechanical alloying synthesis: Nanostructured Fe–30 wt.% Mn alloy was successfully synthesized from high-purity elemental Fe and Mn powders using planetary high-energy ball milling under an argon atmosphere.
🟢 Processing parameters: Two ball-to-powder mass ratios, 20 (S20) and 30 (S30), were investigated to determine the influence of milling intensity on Fe–Mn alloy formation and nanostructural refinement.
🟢 Milling-time effect: Increasing milling time from 5 to 10 h substantially reduced crystallite size and increased lattice strain for both S20 and S30 samples.
🟢 Crystallite refinement: For the S20 condition, crystallite size decreased from 60 nm after 5 h to 16 nm after 10 h of milling.
🟢 High-energy refinement: Increasing the ball-to-powder mass ratio to 30 produced substantially finer crystallites, with crystallite size decreasing from 14 nm after 5 h to only 6 nm after 10 h.
🟢 Lattice-strain increase: Lattice strain increased progressively with both milling time and milling intensity, reaching 1.93% for the S30 sample after 10 h compared with 0.19% for S20 after 5 h.
🟢 Phase transformation: The initial powder mixture consisted of α-Fe and α-Mn phases. At a ball-to-powder ratio of 30, 5 h milling produced a mixture of α-Fe and γ-Fe phases.
🟢 Single γ-phase formation: After 10 h of milling at a ball-to-powder mass ratio of 30, only the nonmagnetic γ-Fe phase was detected and the α-Mn phase disappeared completely, confirming extensive Fe–Mn solid-solution formation.
🟢 Milling-intensity effect: A higher ball-to-powder mass ratio increased milling energy, shortened the diffusion paths required for Fe–Mn solid-solution formation, and produced smaller crystallites with greater lattice strain.
🟢 Lattice-parameter evolution: Changes in XRD peak positions demonstrated modification of the lattice parameter during mechanical alloying, providing evidence of progressive Mn dissolution and Fe–Mn solid-solution development.
🟢 Particle morphology: The initial Fe–Mn powder mixture contained relatively large plate-like particles together with smaller particles and exhibited a broad particle-size distribution.
🟢 Morphological transformation: After 10 h of high-energy milling, the particle morphology changed substantially from plate-like particles toward a more equiaxed morphology.
🟢 Particle-size reduction: Prolonged mechanical milling reduced the average particle size while simultaneously producing relatively large and loose agglomerates as a consequence of deformation and cold welding.
🟢 Homogeneous elemental distribution: SEM/EDS elemental mapping of the 10 h S30 sample demonstrated that Fe and Mn were homogeneously distributed at the atomic scale.
🟢 Solid-solution confirmation: The combination of homogeneous Fe/Mn elemental mapping and XRD results confirmed formation of an Fe–Mn solid solution in the final mechanically alloyed powder.
🟢 Optimal processing condition: Among the investigated conditions, 10 h milling with a ball-to-powder mass ratio of 30 provided the most effective combination for obtaining a homogeneous nanostructured Fe–30Mn alloy with a crystallite size of approximately 6 nm.
🟢 Biomedical relevance: The synthesized nanostructured Fe–30Mn powder was proposed as a potential biodegradable metallic material for the production of temporary medical implants.
Overall, the study demonstrates that milling time and ball-to-powder mass ratio are critical parameters governing the formation of nanostructured Fe–30Mn alloys by mechanical alloying. Increasing the ball-to-powder ratio from 20 to 30 and extending milling to 10 h promoted solid-solution formation, increased lattice strain, transformed the particles from plate-like to equiaxed morphology, and reduced the crystallite size to approximately 6 nm. The resulting homogeneous Fe–Mn nanostructured powder provides a potential starting material for biodegradable metallic implant applications.
ARTICLE LINK
https://doi.org/10.1016/j.mspro.2015.11.134
DOI
10.1016/j.mspro.2015.11.134
HOW TO CITE
Safaie, N.; Khakbiz, M.; Sheibani, S.; Sotoudeh Bagha, P. Synthesizing of Nanostructured Fe-Mn Alloys by Mechanical Alloying Process. Procedia Materials Science 2015, 11, 381–385. DOI: 10.1016/j.mspro.2015.11.134.
KEYWORDS
Mechanical Alloying • Nanostructured Fe–Mn Alloy • X-ray Diffraction • High-Energy Ball Milling • Biodegradable Alloy
Abstract
In the present study, nanostructured Fe-30 wt.% Mn alloys produced by mechanical alloying of Fe and Mn powders mixture. The phase composition and morphology of nanostructured powder were analyzed by X-ray diffraction and scanning electron microscopy. It was found that by milling time up to 10h, crystallite size was decreased to 6 nm, on the contrary lattice strain was increased. Solid solubility levels were determined from changes in the lattice parameter values. The lattice parameter increases slightly from 0.28167 to 0.35776 nm. Increasing milling intensity by higher ball to powder mass ratio resulted in Fe-Mn alloy formation with smaller crystallite size. The SEM results showed that, plate like particles were formed in initial milling time and particles morphology was changed to equiaxed form in final stage of milling process.