Scholarlink

<p>Although hot-rolled La(Fe, Co, Si)<sub>13</sub>-based alloys are promising magnetocaloric materials for solid-state cooling with near-net shaping capabilities, their underlying hot deformation mechanisms remain largely unexplored. In this study, a comprehensive and systematic investigation was conducted, by encompassing the analysis of hot deformation mechanisms, along with the microstructure evolution and magnetocaloric properties of hot-rolled La–Fe–Co–Si alloy. The La<sub>1.05</sub>Fe<sub>11.2</sub>Co<sub>0.7</sub>Si<sub>1.38</sub> alloy was examined using multiscale mechanical analysis to assess the effects of temperature. A series of macroscale hot compression and microscale nanoindentation tests were performed to access global and local mechanical properties, including variations in hardness and indentation modulus of the primary α-Fe and secondary 1:1:1 phases up to 800&#xa0;°C. A significant decrease in hardness and elastic recovery of the secondary phase was observed between 600 and 800&#xa0;°C, above half of its melting point (1113&#xa0;°C), suggesting pronounced flow softening in both the α-Fe and 1:1:1 phases. Additionally, a novel multi-step annealing process was introduced for hot-rolled La–Fe–Co–Si alloys, involving partial transient liquid-phase diffusion in the 1:1:1 phase to address deformation-induced defects, such as residual α-Fe and lattice distortions in the 1:13 phase, which have not been previously reported. As a result, a primary La(Fe, Co, Si)<sub>13</sub> phase with a volume fraction of 97.5% was achieved after multi-step annealing, compared to 87.5% using conventional annealing. Correspondingly, the magnetocaloric properties were restored, with the Curie temperature (<i>T</i><sub>C</sub>) recovering from 276 to 268&#xa0;K and the maximum magnetic entropy change (Δ<i>S</i><sub>M</sub>) increasing from 7.56 to 8.67&#xa0;J&#xa0;kg<sup>−1</sup>&#xa0;K<sup>−1</sup> under a 2&#xa0;T magnetic field.</p> Graphical Abstract <p></p>

错误：搜索内容不能为空，请输入英文关键词
错误：关键词超出字数限制，请精简
高级检索

A systematic study of hot deformation mechanisms in La–Fe–Co–Si alloys and the mitigation of defects in hot rolling process

  • 期刊论文

  • 出版模式：

    开放获取

  • 发表日期：

    2025年5月13日

查看全文
  • Seon Yeong Yang,
  • Min Jik Kim,
  • Hadiseh Esmaeilpoor,
  • Kook Chae Chung,
  • Woo Seok Yang,
  • Jeoung Han Kim,
  • Dong Gun Lee,
  • Kwang Seok Lee,
  • Da Seul Shin

摘要

Although hot-rolled La(Fe, Co, Si)13-based alloys are promising magnetocaloric materials for solid-state cooling with near-net shaping capabilities, their underlying hot deformation mechanisms remain largely unexplored. In this study, a comprehensive and systematic investigation was conducted, by encompassing the analysis of hot deformation mechanisms, along with the microstructure evolution and magnetocaloric properties of hot-rolled La–Fe–Co–Si alloy. The La1.05Fe11.2Co0.7Si1.38 alloy was examined using multiscale mechanical analysis to assess the effects of temperature. A series of macroscale hot compression and microscale nanoindentation tests were performed to access global and local mechanical properties, including variations in hardness and indentation modulus of the primary α-Fe and secondary 1:1:1 phases up to 800 °C. A significant decrease in hardness and elastic recovery of the secondary phase was observed between 600 and 800 °C, above half of its melting point (1113 °C), suggesting pronounced flow softening in both the α-Fe and 1:1:1 phases. Additionally, a novel multi-step annealing process was introduced for hot-rolled La–Fe–Co–Si alloys, involving partial transient liquid-phase diffusion in the 1:1:1 phase to address deformation-induced defects, such as residual α-Fe and lattice distortions in the 1:13 phase, which have not been previously reported. As a result, a primary La(Fe, Co, Si)13 phase with a volume fraction of 97.5% was achieved after multi-step annealing, compared to 87.5% using conventional annealing. Correspondingly, the magnetocaloric properties were restored, with the Curie temperature (TC) recovering from 276 to 268 K and the maximum magnetic entropy change (ΔSM) increasing from 7.56 to 8.67 J kg−1 K−1 under a 2 T magnetic field.

Graphical Abstract