Scholarlink

Abstract <p>Nanocrystalline Co–Ni thin films were successfully synthesized via electrodeposition on copper substrates using a sulfate-chloride bath containing thiourea as a grain refiner. The influence of Ni<sup>2+</sup>/Co<sup>2+</sup> molar ratio on the chemical composition, structural evolution, and thermal stability was systematically investigated. ICP-OES analysis confirmed the anomalous codeposition mechanism, where Co enrichment in the deposits is proportional to its concentration in the electrolyte. Rietveld refinement of XRD patterns revealed a significant phase transition from a Face-Centered Cubic (FCC) dominated structure to a Hexagonal Close-Packed (HCP) phase (up to 80.04%) as the Co content in the bath increased. The incorporation of sulfur (S) from thiourea induced severe lattice distortion, reducing crystallite size to approximately 14 nm while simultaneously increasing microstrain. Differential Scanning Calorimetry (DSC) identified three distinct thermal processes: structural relaxation (40–270°C), HCP↔FCC allotropic transformation (410–420°C), and high-temperature grain coarsening. The 70% Co alloy exhibited the highest thermal stability, suggesting that optimized composition and impurity-induced grain refinement can significantly enhance the metastable properties of electrodeposited iron-group 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

A Comprehensive Study of Co-rich Co–Ni Thin Films: From Nanocrystalline Phase Formation to Structural Relaxation

  • 期刊论文

  • 发表日期：

    2026年7月20日

查看全文
  • Fatima Zohra Bouzit,
  • Hayet Moumeni,
  • Abderrafik Nemamcha

摘要

Abstract

Nanocrystalline Co–Ni thin films were successfully synthesized via electrodeposition on copper substrates using a sulfate-chloride bath containing thiourea as a grain refiner. The influence of Ni2+/Co2+ molar ratio on the chemical composition, structural evolution, and thermal stability was systematically investigated. ICP-OES analysis confirmed the anomalous codeposition mechanism, where Co enrichment in the deposits is proportional to its concentration in the electrolyte. Rietveld refinement of XRD patterns revealed a significant phase transition from a Face-Centered Cubic (FCC) dominated structure to a Hexagonal Close-Packed (HCP) phase (up to 80.04%) as the Co content in the bath increased. The incorporation of sulfur (S) from thiourea induced severe lattice distortion, reducing crystallite size to approximately 14 nm while simultaneously increasing microstrain. Differential Scanning Calorimetry (DSC) identified three distinct thermal processes: structural relaxation (40–270°C), HCP↔FCC allotropic transformation (410–420°C), and high-temperature grain coarsening. The 70% Co alloy exhibited the highest thermal stability, suggesting that optimized composition and impurity-induced grain refinement can significantly enhance the metastable properties of electrodeposited iron-group alloys.