Thermodynamic analysis and effect of temperature on surface hardening of tungsten heavy alloys using ethanol

Highlights: • Surface of tungsten heavy alloys can be hardened using ethanol at 1200–1500 K. • WC shell thickness and reaction zone depth increases with temperature. • Surface hardness (HV_0.3) of the alloy increases from 390 to 1640 with temperature. • Hardening process is controlled by C diffusion to unreacted W through the alloy. - Abstract: Surface hardening of 92.5W–5.25Ni–2.25Fe (wt.%) heavy alloy was investigated at 1200–1500 K using ethanol as carbon source. The hardened surfaces were characterized by XRD, optical microscope and microhardness tester. Microhardness of the alloy increased from HV_0.3 318 to 1640 with temperature. This was attributed to both increased thickness of WC shells formed on W grains and increased reaction depth as a result of higher C diffusion. Reaction pathways leading to WC formation were explained using thermodynamic and experimental results