Study on Cavitation Corrosion Properties of Titanium Alloy Radiation Rod with Different Roughnesses for Ultrasonic Casting

To determine the mechanism of corrosion damage caused by cavitation, the properties of titanium alloy radiation rods with different roughnesses in 2A14 aluminum melt for ultrasonic casting were studied. The corrosion morphology, weight loss/cavitated area, reaction layer and microhardness of surface section were observed, and the collapse of a single cavitation bubble was simulated. The weight loss/cavitated area caused by the physical impact of cavitation accounted for 6.4% to 8.6% of the total weight loss/cavitated area. The corrosion product was TiAl3. The reactant appeared at the Al/Ti solid–liquid interface in 4 min and the reaction layer appeared in 10 min under different roughnesses. The thickness of the work hardening layer on the surface of the material could reach 160 μm. The results show that the greater the roughness of titanium alloy in aluminum melt, the greater the rate of weight loss/cavitated area and the greater the maximum pressure in the process of cavitation bubble collapse. The evolution of the hardened layer depended on the stripping rate of the surface material caused by cavitation corrosion and the work hardening rate of the surface layer. This study provides insights to develop a new homemade Ti alloy radiation rod with better resistance to corrosion in the ultrasonic casting.