Effects of Rolling Reduction and Strength of Composed Layers on Bond Strength of Pure Copper and Aluminium Alloy Clad Sheets Fabricated by Cold Roll Bonding

Yoji Miyajima,Masaharu Kato,Kotaro Iguchi,Susumu Onaka

doi:10.1155/2014/614821

Yoji Miyajima, Masaharu Kato + Show 2 more

Open Access

https://doi.org/10.1155/2014/614821

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Abstract

Three types of clad sheets, Cu/Al, Cu/AA5052, and Cu/AA5083, were produced by cold roll bonding with the rolling reduction of 50% and 75%. Tensile shear tests which give tensile shear strength were performed in order to assess the bond strength. Scanning electron microscopy was performed on the fractured interface produced by the tensile shear tests, which suggests that the fracture occurs within the Al alloy layer. The tensile shear strengths considering the area fraction of deposit of Al alloy on Cu side were compared with the shear stress converting from the ultimate tensile strengths. As a result, the tensile shear strength of the clad sheets is attributed to the shear strength of Al alloy layer close to the well bonded interface. A simple model was proposed that explains the effects of the rolling reduction and area fraction of deposit of Al alloy.

Highlights

Composite materials which have superior characteristics compared with each composed material are widely used, and metals can be used as the composed materials
It is possible to form the bonding without intermetallic layers by cold roll bonding since the critical diffusion does not occur at the low process temperature
It should be noted that the above assumption is not satisfied once necking occurs after true stress reaches ultimate tensile strength (UTS), but such plastic instability region of ss curves should be treated as advisory values

Summary

Introduction

Composite materials which have superior characteristics compared with each composed material are widely used, and metals can be used as the composed materials. Cu/Al composites have smaller density than Cu and higher thermal and electrical conductivities than Al [1]; they are used as light weight electric wires Such metallic composites can be fabricated by mechanical alloying, diffusion bonding, and roll bonding. Intermetallic layers are often formed at the interfaces of clad sheets Such intermetallic layers would reduce the bond strength for Cu/Al composites [1]. Three types of Al alloys are chosen with strength lower than, nearly equal to, and higher than that of Cu. In the present study, three types of Al alloys are chosen with strength lower than, nearly equal to, and higher than that of Cu Using these alloy combinations, we will investigate the effect of rolling reduction and strength of composed metallic layers on bond strength of Cu/Al alloy clad sheets

Materials and Methods

Results and Discussion

Conclusions