The Mechanical Properties of a Transient Liquid Phase Diffusion Bonded SSM-ADC12 Aluminum Alloy with a ZnAl4Cu3 Zinc Alloy Interlayer

Abstract

In this study, the mechanical properties of SSM-ADC12 aluminum alloy specimens with a ZnAl4Cu3 zinc alloy interlayer were observed after Transient Liquid Phase Diffusion Bonding (TLPDB), a welding process conducted in a semi-solid state. The purpose of the experiment was to study how the following parameters—bonding temperature (400, 430, 460, 490, and 520 °C), bonding time (60, 90, and 120 min), and thickness of the ZnAl4Cu3 zinc alloy (0.5, 1.0, and 2.0 mm)—affect the mechanical properties and the types of defects that formed. The results show that the bonding strength varied significantly with different parameters following the TLPDB process. A maximum bonding strength of 32.21 MPa was achieved at a bonding temperature of 490 °C, with 20 min of bonding and a ZnAl4Cu3 zinc alloy layer that was 2.0 mm thick. Conversely, changing the welding parameters influenced the bonding strength. A minimum bonding strength of 2.73 MPa was achieved at a bonding temperature of 400 °C, with a bonding time of 90 min and a ZnAl4Cu3 zinc alloy interlayer that was 2.0 mm thick. The Vickers microhardness results showed that the bonded zone had a lower hardness value compared to the base materials (BMs) of the SSM-ADC12 aluminum alloy (86.60 HV) and the ZnAl4Cu3 zinc alloy (129.37 HV). The maximum hardness was 83.27 HV, which resulted from a bonding temperature of 520 °C, a bonding time of 90 min, and a ZnAl4Cu3 zinc alloy that was 2.0 mm thick. However, in the near interface, the hardness value increased because of the formation of MgZn2 intermetallic compounds (IMCs). The fatigue results showed that the stress amplitude was 31.21 MPa in the BMs of the SSM-ADC12 aluminum alloy and 20.92 MPa in the material that results from this TLPDB process (TLPDB Material) when the limit of cyclic loading exceeded 106 cycles. Microstructural examination revealed that transformation from a β-eutectic Si IMC recrystallization structure to η(Zn–Al–Cu) and β(Al2Mg3Zn3) IMCs occurred. A size reduction to a width of 6–11 µm and a length of 16–44 µm was observed via SEM. Finally, voids or porosity and bucking defects were found in this experiment.