Abstract
Bulk Mn52Al46C2 in τ-phase was prepared by vacuum induction melting and used as precursor for the production bulk permanent magnets by suction casting and hot-extrusion. Part of the precursor alloy was mechanically milled into a τ-phase powder and used as precursor for production of samples by electron beam melting, hot-compaction and high pressure torsion processes. The microstructure and magnetic properties of all samples were investigated and correlated. It was found that the mechanical deformation enhances coercivity, up to 0.58 T, while the absence of this strain is beneficial for magnetization. Among the observed techniques, hot extrusion and high pressure torsion have shown promising possibilities to further develop Mn-Al-C as permanent magnets. However, it should be taken into account the challenges related to design a proper processing window for hot extrusion and the limitation of HPT regarding the absence of texture.
Highlights
Mn-Al alloys belong to the well-known material systems, which have been intensively studied since the late 60’s as perspective candidates for use as permanent magnets (PM) [1,2], but faded into oblivion after the discoveryof the Nd-Fe-B magnets in the 80’s [3]
Energy-dispersive X-ray spectroscopy (EDS) measurements were performed to quantify chemical composition of the present phases.In addition, EDS measurements were taken in larger portions of the sample to ensure the Mn/Al ratio was preserved after each processing technique
To investigate the influence of different production methods of bulk Mn-Al-C based permanent magnets on their magnetic properties, a batch of Mn52Al46C2 precursor alloy was prepared by vacuum induction melting for further processing
Summary
Mn-Al alloys belong to the well-known material systems, which have been intensively studied since the late 60’s as perspective candidates for use as permanent magnets (PM) [1,2], but faded into oblivion after the discoveryof the Nd-Fe-B magnets in the 80’s [3]. The effect of each specific defect on the magnetic properties is still under investigation, as different characterization techniques are necessary to obtain qualitatively and/or quantitatively data about the densityand distribution of these defects These microstructural features are very often reported to coexist, which increase the challenge to understandthe coercivity mechanism in t-MnAl-based compounds. Based on these factors, a complete understand of the processing route on the phase stability, microstructure and magnetic properties are indispensableto optimize the MnAl material system to be suitable for permanent magnet applications. This present work is focused on the use of five different processing techniques for production of Mn-Al-C bulk samples and the correlation between microstructure and magnetic properties for each of these processes
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