Integrated control mechanism of ultrasound and ZrO2 particles on differential microstructures for the wire arc additive manufacturing

Inhibiting unhomogenised microstructure during the directed energy deposition process with the electric arc energy source (DED-Arc) has become a significant challenge. Ultrasonic vibration leads to the severe stirring of liquid metal and break down dendrites in the inner-layer zone, which promotes the formation of fine grains after rapid solidification. In contrast, the grain refinement effect is not obvious in the semi-melting zone. The addition of ZrO2 particles in the 2319 Al-Cu alloy during the DED-Arc process can drag and pin the grain boundary to prevent grain coarsening in the semi-melting zone. Under the integrated effect of ultrasound and particles, ZrO2 particles can be evenly distributed in different regions, which is beneficial to enhance the microstructure uniformity of the deposition layer and ultimately achieving significant improvement in mechanical properties. The intergrated effect of ultrasonic vibration and particles on strength and elongation reach 13.8% and 92.4%, respectively.