Effect of ultra-fine powders on the microstructure of Ti(CN)– xWC–Ni cermets

• Published in: Acta materialia Vol. 52; no. 6; pp. 1379 - 1386
• Main Authors: Jung, Jinkwan, Kang, Shinhoo
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 05-04-2004; Elsevier Science
• Subjects: Cermets; Cermets, ceramic and refractory composites; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Materials science; Mechanical properties; Microstructure; Other materials; Physics; Sintering; Specific materials; Ultra-fine powders; Mechanical properties; Cermets; Microstructure; Sintering; Ultra-fine powders; Titanium carbonitride; Nickel alloys; Cemented carbides; Powder sintering; Experimental study; Ultrafine powder; Tungsten carbides
• ISSN: 1359-6454; 1873-2453
• DOI: 10.1016/j.actamat.2003.11.021

Microstructural and compositional analyses of Ti(CN)–
xWC–20Ni cermets were done in order to better understand the dissolution behavior of ultra-fine sized Ti(CN) and WC in comparison with a micro-sized system. The WC content was varied from 5 to 75 wt%. A discrete composition (∼50 wt%WC addition) at which WC does not dissolve any longer in the ultra-fine system was found. At this composition, the W concentrations, not only in the rim, (Ti,W)(CN), but in the binder as well were at a maximum. Depending on the powder size and morphology, these values are strongly affected due to the surface areas of Ti(CN) and WC for dissolution and precipitation sites. Furthermore, a significant improvement in the mechanical properties of simple ultra-fine systems was found, compared to that of corresponding micron-sized systems (Hv 14–15 GPa,
K
IC 8–10 MPa m
1/2), which are comparable to commercial cermets. The refined microstructure and high fraction of rim phase in the ultra fine systems are likely responsible for this difference.