Optimizing degassing for particle-reinforced Al composite: Advanced ultrasonic-assisted argon treatment and numerical...

Hydrogen removal from particle-reinforced Al composite is critical for preventing porosities near particle clusters and improving comprehensive material properties. This study investigated the effects of different argon flow schemes and power ultrasound on bubble dispersion in water. Based on similarity theory, the optimal argon flow scheme for ultrasonic-assisted argon (UAA) treatment was identified and applied to TiB₂/2024 Al composite to explore the degassing mechanism. Three argon flow schemes for UAA treatment: EV-EC (External ventilation, equal channel), IV-EC (Internal ventilation, equal channel), and IV-RC (Internal ventilation, reduced channel) were evaluated through numerical simulation and water simulation experiments. The results demonstrated that IV-RC scheme exhibits superior bubble dispersion characteristics and a broader bubbling range. Experimental results in Al composite confirmed that UAA treatment with IV-RC scheme achieved the highest degassing efficiency, with a relative density improvement of up to 98.01 % and the lowest hydrogen content (0.0235 ppm). Synchrotron radiation X-ray computed tomography results indicated that UAA treatment effectively reduces the pore size and volume, transforming interconnected, complex pores into dispersed, nearly spherical ones. Ultrasonic cavitation aids this process by breaking small argon bubbles into numerous tiny bubbles that penetrate deeply into the melt, reducing the wettability angle between particles and the matrix and thereby improving hydrogen removal efficiency.