Effect of Vacuum Heat Treatment on Microstructures and Mechanical Properties of 7A52 Aluminum Alloy-Al2O3 Ceramic Brazed Joints

Deku Zhang,Xusheng Qian,Xiaopeng Li,Kehong Wang

doi:10.3389/fmats.2021.634658

Deku Zhang, Xusheng Qian + Show 2 more

Open Access

https://doi.org/10.3389/fmats.2021.634658

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Abstract

This study investigated the interface morphology, microstructure composition and connection strength of 7A52 aluminum alloy-Al2O3 ceramic brazed joints under heat treatment conditions. Alumina ceramics were first treated with electroless nickel plating, followed by vacuum heat treatment at different temperatures. Then an Al-Si-Mg intermediate layer was placed between the treated alumina ceramic and 7A52 aluminum alloy for brazing under the conditions of welding temperature 590, holding time 1h, pressure 2 MPa. Results showed that when heat treatment was performed at 350°C and below, the nickel-plated metal had an amorphous structure, and when performed at 400°C, the nickel-plated layer had a crystalline structure and the brittle phase Ni3P was precipitated. When the heat treatment temperature was 350°C, the joint shear strength reached the maximum, which was 68.7 MPa.

Highlights

Aluminum alloy has been widely used in structural parts of airplanes, rockets, ships and lightweight vehicles since its excellent mechanical properties and high specific strength
From Al2O3 ceramic to aluminum alloy, according to the above analysis, the following zones existed at the joint interface: Zr-ceramic reaction zone, solder zone, Al-Ni intermetallic compound zone, AlSi eutectic zone
According to the results of XRD diffraction analysis, when heat treatment was performed at 350°C and below, the nickel-plated metal had an amorphous structure, and when performed at 400°C, the nickel-plated layer had a crystalline structure and the brittle phase Ni3P was precipitated

Summary

Introduction

Aluminum alloy has been widely used in structural parts of airplanes, rockets, ships and lightweight vehicles since its excellent mechanical properties and high specific strength. The interface morphology, microstructure composition and connection strength of 7A52 aluminum alloy-Al2O3 ceramic brazed joints under heat treatment conditions were investigated.

Results

Conclusion