Growth and Microstructure‐Dependent Hardness of Directionally Solidified WC–W2C Eutectoid Ceramics

Directionally solidified WC–W₂C ceramics containing 40 at% carbon, corresponding to the WC–W₂C eutectoid composition, were produced by laser surface melt processing. The resulting microstructures showed a lamellar‐type eutectic/eutectoid microstructure with the WC minor phase embedded in the W₂C matrix phase. The interlamellar spacing (λ) in the eutectoid regions followed the relationship Vλ^3.8 = constant, with the smallest spacing of 331 ± 36 nm achieved in the 3.24 mm/s processed sample. The indentation hardness increased with decreasing interlamellar spacing, and a Vickers indentation hardness of 28.5 GPa was achieved in the sample with the smallest interlamellar spacing. The directionally solidified WC–W₂C materials show enhanced indentation mechanical properties in comparison to previously reported WC–Co composites and WC‐based materials.