Structure and microhardness of cu-ta joints produced by explosive welding

Area of Science:

• Materials Science
• Metallurgy
• Welding Engineering

Background:

• Copper-tantalum (Cu-Ta) joints are crucial in various industrial applications.
• Understanding the microstructural evolution and mechanical properties of explosively welded Cu-Ta joints is essential for optimizing their performance.

Purpose of the Study:

• To investigate the structure and microhardness of Cu-Ta joints fabricated by explosive welding.
• To analyze the formation mechanism of the intermediate layer and its microstructural characteristics.
• To evaluate the effect of post-weld heating on the properties of the Cu-Ta joint.

Main Methods:

• Explosive welding was employed to create Cu-Ta joints.
• Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used for microstructural analysis.
• Microhardness testing (Vickers hardness) was performed on the joint and base materials.
• The influence of heating temperatures from 100°C to 900°C was examined.

Main Results:

• An intermediate layer (20–40 μm) with a finely dispersed heterophase structure formed between Cu and Ta plates.
• This layer contained microvolumes of tantalum particles in a copper matrix and copper particles in a tantalum matrix.
• The microhardness of the intermediate layer reached 280 HV, significantly higher than that of pure copper (~130 HV) and tantalum (~160 HV).
• Heating to 900°C reduced the intermediate layer's microhardness to 150 HV, primarily due to structural changes in copper.

Conclusions:

• Explosive welding is an effective method for producing high-hardness Cu-Ta joints with a unique intermediate layer.
• The heterophase structure of the intermediate layer contributes to enhanced microhardness.
• Post-weld heat treatment significantly affects the mechanical properties, with high temperatures leading to a decrease in hardness due to copper's structural transformations.