Ultrafast ultrasonic-assisted transient liquid bonding Al/Mg in air

We used ultrasonic-assisted transient liquid bonding (UATLP) to join dissimilar Al/Mg alloys with pure Zn interlayer in the air to prevent the formation of Al-Mg intermetallic compounds (IMCs). The effects of bonding temperature, ultrasonic power, sonotrode pressure, and interlayer thickness on the microstructure and mechanical properties of the bonded joints were studied. Results showed that the addition of Zn interlayer could effectively depress the Al-Mg IMCs. The oxide layer on the Al substrate is incompletely removed at bonding temperature below 380 degrees C, the Mg side is bonded by eutectic phase, and the Al side is bonded by diffusion. The joint is characterized by Mg-Zn eutectic (containing ternary IMCs) and IMCs of MgZn and MgZn2 layer. MgZn2 is the weak point of the joint under such a condition, and the joint has shear strength of approximately 20 MPa. The oxide layer on the Al substrate is completely removed when the temperature exceeds 380 degrees C, the large amount of Al that flows into the joint results in a Mg32(Al,Zn)49 layer adjacent to the Al substrate. The joint gains its maximum strength of 28.4 MPa when thin MgZn2 and discontinuous Mg32(Al,Zn)49 exist adjacent to the Al substrate. High ultrasonic power, large sonotrode pressure, and thin Zn interlayer could reduce the thickness of MgZn2.

Automated summary

In this study, ultrasonic-assisted transient liquid bonding (UATLP) was used to join dissimilar Al/Mg alloys with a pure Zn interlayer in the air to prevent the formation of Al-Mg intermetallic compounds (IMCs). The effects of bonding temperature, ultrasonic power, sonotrode pressure, and interlayer thickness on the microstructure and mechanical properties of the bonded joints were investigated. It was found that the addition of a Zn interlayer effectively suppressed the formation of Al-Mg IMCs. The study also revealed that high ultrasonic power, large sonotrode pressure, and thin Zn interlayer could reduce the thickness of MgZn2.