Composition and property optimization of rare-earth-free Mn-Al-C magnet by phase stability and magnetic behavior analysis

Sumin Kim, Minyeong Choi, Hoyun Won, Hyun Sook Lee, Wonchel Lee, Seong Gon Kim, Wooyoung Lee, Yang Ki Hong

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1 Citation (Scopus)


Mn-Al-C system offers a possibility of rare-earth-free permanent magnets with the reduced temperature-dependent deterioration of magnetic properties. The Mn-Al-C alloy composition and magnetic properties have been optimized via calculations of electronic structures and phase stability of L10-ordered ferromagnetic τ-phase (Mn0.5Al0.5)100−xCx. The WIEN2k program package, Vienna Ab-initio simulation package (VASP), and Alloy Theoretic Automated Toolkit (ATAT) were used to calculate and identify the optimal carbon content for the most stable τ-phase of the L10-structured Mn-Al-C. We used the Brillouin function and Callen-Callen semiempirical relation to obtain the saturation magnetization and magnetocrystalline anisotropy constant at elevated temperatures. It was found that a carbon content of 2.33 at% gives the most stable τ-phase L10 (Mn0.5Al0.5)100−xCx that has the lowest formation energy and highest saturation magnetization among the studied carbon contents (x = 0–3.03 at%). The magnetocrystalline anisotropy constant at 0 K increases with increasing the carbon content. Therefore, the carbon-doped Mn-Al becomes magnetically harder than the pure Mn50Al50. However, the anisotropy constant decreases at 300 K as the carbon content increases. The Curie temperature decreases to 590 K at x = 2.33 from 685 K at x = 0.0. The estimated saturation magnetization was approximately 130 emu/g at 300 K, leading to 18 MGOe under Bs = Br and Hci> Br/2. Therefore, it is highly probable that Mn-Al-C potentially fills the gap between 10 and 30 MGOe magnets. The results in this study quantify and explain the reason for widely studying the approximately 2 at% carbon-doped Mn-Al systems.

Original languageEnglish
Article number165773
JournalJournal of Alloys and Compounds
Publication statusPublished - 2022 Oct 25

Bibliographical note

Funding Information:
This study was supported by the National R&D Program (NRF- 2020M3H4A2084420 ), the Technology Innovation Program ( MOTIE-20013621 , Center for Super Critical Material Industrial Technology), and the Priority Research Centers Program (NRF- 2019R1A6A1A11055660 ). Here, NRF is the National Research Foundation of Korea (NRF) funded by the Ministry of Science and ICT in Republic of Korea and MOTIE is the Ministry of Trade, Industry & Energy in Republic of Korea. This study was also supported by the US National Science Foundation Civil, Mechanical, and Manufacturing Innovation Division (NSF-CMMI) under award number 1463301, United States (MYC, HYW, WCL, YKH). H.-S. Lee acknowledges support from the Basic Research in Science and Engineering Program ( NRF-2021R1A2C1013690 ), Republic of Korea.

Publisher Copyright:
© 2022 Elsevier B.V.

All Science Journal Classification (ASJC) codes

  • Mechanics of Materials
  • Mechanical Engineering
  • Metals and Alloys
  • Materials Chemistry


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