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Suppressing η‐phase development in steel‐cemented tungsten carbide: A spark plasma sintering study
Author(s) -
Cahill James T.,
Kelly James P.,
Novitskaya Ekaterina,
McKee Michael,
Bahena Joel A.,
Graeve Olivia A.
Publication year - 2019
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/jace.15814
Subject(s) - spark plasma sintering , materials science , tungsten carbide , sintering , vanadium carbide , metallurgy , carbide , fracture toughness , vanadium , tungsten , cemented carbide , phase (matter) , indentation hardness , brittleness , tool steel , microstructure , chemistry , organic chemistry
We describe the phase stability of a cemented tungsten carbide prepared using a high‐vanadium tool steel as the cementing/binder phase and confirm suppression of (Fe, W) 6 C η‐phase formation, attributed to the preferential formation of a V 0.78 W 0.22 C 1− x phase that exists as islands within the Fe‐rich binder matrix. The samples were prepared using spark plasma sintering (SPS), starting from commercially available WC and A11‐LVC tool steel powders. The starting powders were ball milled adding 10, 15, and 20 vol.% steel. An A11‐LVC tool steel was chosen as a low‐cost hard steel (49 HRC) that does not contain Ni or Co but has a high vanadium (~9 wt.%) and carbon (~1.75 wt.%) content. Our results show that sintering by SPS can produce high‐density (>98%) WC‐steel specimens in which the matrix wets the WC grain surfaces and formation of the brittle η‐phase is avoided. The η phase is often regarded as embrittling and undesirable, and its presence can result in degradation of mechanical properties. Microhardness values for the WC‐10 and WC‐15 vol.% steel samples were 12.3 ± 1.2 and 13.0 ± 0.9 GPa, respectively, whereas the fracture toughness values were 8.83 ± 0.48 and 8.81 ± 0.61 MPa·m 1/2 , respectively.