Microstructural Control of the Interface Layer for Strength Enhancement of Dissimilar Al/Cu Joints via Ni Addition during TIG Arc Brazing

Hiroki S Furuya,Sakiko Yabu,Hiroyuki Kokawa,Yutaka S Sato

doi:10.3390/met11030491

Hiroki S Furuya, Sakiko Yabu + Show 2 more

Open Access

https://doi.org/10.3390/met11030491

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Journal: Metals	Publication Date: Mar 16, 2021
Citations: 4	License type: CC BY 4.0

Affiliation: Tohoku University, Shanghai Jiao Tong University

Abstract

Dissimilar metal joining between Al and Cu is effective for reducing the weight and cost of electrical components. In this study, dissimilar lap joining of pure Al to pure Cu with an Al-Ni filler material was conducted using tungsten inert gas (TIG) arc brazing, and the effect of Ni on the joint strength associated with the microstructure of the intermetallic compound (IMC) layer at the dissimilar interface was examined. The addition of Ni effectively increased the interfacial strength of the joints. Regardless of the addition of Ni, the joints fractured in the thick Al2Cu layer formed at the Al/Cu interface. However, the Ni addition reduced the thickness of the IMC layer and led to the formation of Al7Cu4Ni particles in the weakest Al2Cu layer. Both the thickness reduction and reinforcing Al7Cu4Ni particle formation are thought to contribute to the increase in joint strength of the Al/Cu dissimilar interface.

Highlights

A multimaterial structure of dissimilar metals is required for performance improvement in commercial products
The effect of the addition of Ni to the Al filler material on the strength associated with the microstructure of the intermetallic compound (IMC) layer at the Al/Cu dissimilar joint interface was examined
Our research group previously showed that the strength of the Al/Cu dissimilar joint obtained via laser brazing was improved by the addition of Ni, resulting from the formation of a (Cu,Ni)Al layer at the weak interface between the Al2Cu and Al4Cu9 layers [34], which is a different mechanism obtained in this study

Summary

Introduction

A multimaterial structure of dissimilar metals is required for performance improvement in commercial products. The formation of an ideal structure in practical applications may require the dissimilar joining of Al alloy to Cu. Mechanical joining [3] has potential as a solution for the dissimilar joining, but it generally results in an increase in weight of the products, which may be unaccepted in practical use. Metallurgical joining is often required as a suitable technique without an increase in weight of the products. A sound metallurgical joint is a great challenge to achieve because of the formation of an intermetallic compound (IMC) layer [4,5,6] at the Al/Cu dissimilar interface through mutual diffusion during the joining process. The IMCs exhibit low ductility [5,7], resulting in a significant decrease in the interfacial strength of the Al/Cu joint

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