Exploring accurate structure, composition and thermophysical properties of eta carbides in 17.90 wt% W-4.15 wt% Cr-1.10 wt% V-0.69 wt% C steel

The heat resistance of the eta carbides is important for red hardness and hot strength of high tungsten iron-base alloys. The crystal structure and exact composition of eta carbides in this work are revealed to be cubic, Fe3.01W2.33Cr0.38V0.28C1.06 by extraction, X-ray diffraction refinement and electron probe micro-analysis. Defect formation energy calculations show that Cr and V occupy W sites in the lattice. Cr and V decrease the mechanical properties and weaken the elastic heat resistance of eta carbides, which is attributed to the C-Cr and C-V bonds weaker than C-W bonds and the C-Cr bonds population decrease at high temperature. Published by Elsevier Ltd on behalf of Acta Materialia Inc.