Scholarlink

<p>It is well known that microstructural refinement, a key strengthening mechanism in metallic alloys, can be enhanced by the high solidification rates inherent to laser surface treatment techniques. However, the influence of laser power on the microstructural evolution and hardness response of CoCrNi-based medium-entropy alloys remains insufficiently explored. In this study, the surface of arc-melted Cr<sub>45</sub>Co<sub>27.5</sub>Ni<sub>27.5</sub> (at%) alloy was laser remelted using powers of 200&#xa0;W, 300&#xa0;W, and 400&#xa0;W to assess the effect of power input on microstructure and hardness. X-ray diffraction, optical microscopy, scanning electron microscopy, electron backscatter diffraction, and dynamic ultramicrohardness testing were employed for characterization. While the 400&#xa0;W condition led to excessive melting and proved more suitable for welding applications than for surface refinement, a notable increase in hardness was observed, from 181 ± 11 kgf/mm² in the substrate to 232 ± 66 kgf/mm² (200&#xa0;W) and 236 ± 28 kgf/mm² (300&#xa0;W) on the remelted surfaces, which maintained their single-phase FCC microstructure. This improvement is attributed to both grain refinement (≈ 25&#xa0;μm for the laser tracks compared to 92&#xa0;μm for the substrate) and the formation of refined cellular structures measuring 1.9 ± 0.3&#xa0;μm (200&#xa0;W) and 4.9 ± 2.2&#xa0;μm (300&#xa0;W), compared to the coarser microstructure of the substrate. These findings provide new evidence that laser remelting with controlled power can effectively tailor the surface microstructure and mechanical response of CoCrNi medium-entropy alloys.</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

Effect of laser power on microstructure and hardness of a Cr-Co-Ni medium-entropy alloy

  • 期刊论文

  • 发表日期：

    2025年11月21日

查看全文
  • Maria Helena Teles Lopes,
  • Adilson Vitor Rodrigues,
  • Pablo Miguel de Souza,
  • Guilherme Cardeal Stumpf,
  • Eric Marchezini Mazzer,
  • Francisco Gil Coury,
  • Andres Felipe Ramirez,
  • João Batista Fogagnolo,
  • Pedro Henrique Rodrigues Pereira,
  • Dagoberto Brandão Santos,
  • Witor Wolf

摘要

It is well known that microstructural refinement, a key strengthening mechanism in metallic alloys, can be enhanced by the high solidification rates inherent to laser surface treatment techniques. However, the influence of laser power on the microstructural evolution and hardness response of CoCrNi-based medium-entropy alloys remains insufficiently explored. In this study, the surface of arc-melted Cr45Co27.5Ni27.5 (at%) alloy was laser remelted using powers of 200 W, 300 W, and 400 W to assess the effect of power input on microstructure and hardness. X-ray diffraction, optical microscopy, scanning electron microscopy, electron backscatter diffraction, and dynamic ultramicrohardness testing were employed for characterization. While the 400 W condition led to excessive melting and proved more suitable for welding applications than for surface refinement, a notable increase in hardness was observed, from 181 ± 11 kgf/mm² in the substrate to 232 ± 66 kgf/mm² (200 W) and 236 ± 28 kgf/mm² (300 W) on the remelted surfaces, which maintained their single-phase FCC microstructure. This improvement is attributed to both grain refinement (≈ 25 μm for the laser tracks compared to 92 μm for the substrate) and the formation of refined cellular structures measuring 1.9 ± 0.3 μm (200 W) and 4.9 ± 2.2 μm (300 W), compared to the coarser microstructure of the substrate. These findings provide new evidence that laser remelting with controlled power can effectively tailor the surface microstructure and mechanical response of CoCrNi medium-entropy alloys.