| Abstract Scope |
An ultrafast boriding process was used to fabricate a composite boride coating comprising WB₄ and ReB₂ on a W–25 wt.% Re alloy in a borax-based molten-salt electrolyte at 1000 °C for 10 minutes. The resulting layer was approximately 10 µm thick and exhibited a dense duplex microstructure composed primarily of WB₄ and ReB₂ phases. Nanoindentation measurements showed hardness exceeding 40 GPa. Tribological tests against a sapphire ball showed a friction coefficient of 0.15 for the borided surface, whereas the untreated W–25 wt.% Re alloy showed a higher coefficient of approximately 0.25 under identical conditions. Post-test microscopic and spectroscopic analyses revealed negligible wear on the borided surface, while the unborided alloy experienced significant material degradation. Overall, the formation of superhard boride phases on the WRe alloy provided near-wearless performance, indicating strong potential for applications involving extreme tribological conditions. |