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<p>The simultaneous improvement of strength, ductility and toughness in cast iron alloys is a key goal in the metallurgical industry. A promising strategy to achieve that is to modify the alloys by adding nanoparticles with high hardness and thermal resistance. Two valuable examples are titanium carbide (TiC) and titanium nitride (TiN) which have been reported to originate microstructural changes in Fe-based alloys and to enhance their mechanical properties. A base cast iron with a high Mg content and a low Si content was first produced and then remelted with or without the addition of either TiC or TiN nanoparticles (about 20&#xa0;nm in diameter). The resulting alloys were cast in a metallic mold using two methods: centrifugation to produce medals and gravity to produce bars. In the former case, the modified castings were produced with the addition of about 3.8% of nanoparticles while these additions were about 1.0% for the latter case. The nanoparticles were previously introduced in Ni crucibles to promote good wettability. All produced castings showed a matrix composed of a high fraction of carbides, areas with pearlite (medals) or with martensite (bars), low density numbers of small graphite nodules and limited areas with Chunky graphite which were also detected on two bars. The present work is focused on characterizing all the small non-graphitic microparticles detected in the matrix of the produced alloys using EDS–SEM microanalysis. These particles were found in both carburic and pearlitic/martensitic areas and they were containing Mg or Ti as main element. Emphasis was put on Ti-rich particles that were mostly TiC and to a minor extent TiN in all samples, including alloys without the addition of nanoparticles, though their density number was lower in these latter. The average sizes of the Ti-bearing particles finally obtained were around 300&#xa0;nm, i.e., much bigger than the NPs initially added (about 20&#xa0;nm), which suggests that they could form by epitaxial growth, epitaxial regrowth and/or direct precipitation from the liquid. These results questioned the possibility of reinforcing cast iron alloys with nanoscale particles under the present experimental conditions. Different parameters have been proposed to evaluate either the incorporation level of the added nanoparticles and the homogeneity of the distributions in the produced alloys.</p>

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Structural Characterization of Cast Iron Alloys Produced with the Addition of TiC and TiN Nanoparticles Using Metallic Molds

  • 期刊论文

  • 发表日期：

    2026年3月12日

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  • Garazi Ereña,
  • Izaskun Gil de Muro,
  • Beatriz González,
  • Jacques Lacaze,
  • Jon Sertucha

摘要

The simultaneous improvement of strength, ductility and toughness in cast iron alloys is a key goal in the metallurgical industry. A promising strategy to achieve that is to modify the alloys by adding nanoparticles with high hardness and thermal resistance. Two valuable examples are titanium carbide (TiC) and titanium nitride (TiN) which have been reported to originate microstructural changes in Fe-based alloys and to enhance their mechanical properties. A base cast iron with a high Mg content and a low Si content was first produced and then remelted with or without the addition of either TiC or TiN nanoparticles (about 20 nm in diameter). The resulting alloys were cast in a metallic mold using two methods: centrifugation to produce medals and gravity to produce bars. In the former case, the modified castings were produced with the addition of about 3.8% of nanoparticles while these additions were about 1.0% for the latter case. The nanoparticles were previously introduced in Ni crucibles to promote good wettability. All produced castings showed a matrix composed of a high fraction of carbides, areas with pearlite (medals) or with martensite (bars), low density numbers of small graphite nodules and limited areas with Chunky graphite which were also detected on two bars. The present work is focused on characterizing all the small non-graphitic microparticles detected in the matrix of the produced alloys using EDS–SEM microanalysis. These particles were found in both carburic and pearlitic/martensitic areas and they were containing Mg or Ti as main element. Emphasis was put on Ti-rich particles that were mostly TiC and to a minor extent TiN in all samples, including alloys without the addition of nanoparticles, though their density number was lower in these latter. The average sizes of the Ti-bearing particles finally obtained were around 300 nm, i.e., much bigger than the NPs initially added (about 20 nm), which suggests that they could form by epitaxial growth, epitaxial regrowth and/or direct precipitation from the liquid. These results questioned the possibility of reinforcing cast iron alloys with nanoscale particles under the present experimental conditions. Different parameters have been proposed to evaluate either the incorporation level of the added nanoparticles and the homogeneity of the distributions in the produced alloys.