The influence of silicon content on the microstructure and high‐temperature oxidation behavior of aluminum‐silicon coatings on Ti‐6Al‐4 V alloy by hot dipping route

Abstract

AbstractThe poor high‐temperature oxidation properties of Ti‐6Al‐4 V (titanium‐aluminum‐vanadium) alloy limit its applications under high‐temperature components of aero‐engines. In this study, the aluminum‐silicon coatings with different silicon content were fabricated on titanium‐aluminum‐vanadium alloy via the hot dipping route. A metallurgical bond was established at the interface between aluminum‐silicon coatings and substrates following the hot dipping. The results showed that three different coatings were formed: titanium(aluminum, silicon)3+ liquid‐(aluminum, silicon), titanium(aluminum, silicon)3+ τ2+ liquid‐(aluminum, silicon) and τ1+ τ2+ liquid‐(aluminum, silicon). Furthermore, the formation of aluminum‐silicon coatings was analyzed by diffusion path theory. The coated alloy was subjected to a high‐temperature oxidation test at 850 °C, and the weight gains were only 5.1 % to 22.4 % of the bare alloy. The coatings improved the high‐temperature oxidation resistance of titanium‐aluminum‐vanadium alloy. The most favorable oxidation behavior was noticed for the titanium(aluminum, silicon)3+liquid‐(aluminum, silicon) coatings. The higher the silicon content in titanium(aluminum, silicon)3+liquid‐(aluminum, silicon) coatings, the more excellent high‐temperature oxidation resistance was achieved.