Novel strip-cast Mg/Al clad sheets with excellent tensile and interfacial bonding properties.

Jung-Su Kim,Seung-Pill Jung,Sunghak Lee,Kwang Seok Lee,Junhan Yuh,Dong Ho Lee,Byeong-Joo Lee,Hyoung Seop Kim,Young Won Chang,Ki Jong Kim

doi:10.1038/srep26333

Abstract

In order to broaden industrial applications of Mg alloys, as lightest-weight metal alloys in practical uses, many efforts have been dedicated to manufacture various clad sheets which can complement inherent shortcomings of Mg alloys. Here, we present a new fabrication method of Mg/Al clad sheets by bonding thin Al alloy sheet on to Mg alloy melt during strip casting. In the as-strip-cast Mg/Al clad sheet, homogeneously distributed equi-axed dendrites existed in the Mg alloy side, and two types of thin reaction layers, i.e., γ (Mg17Al12) and β (Mg2Al3) phases, were formed along the Mg/Al interface. After post-treatments (homogenization, warm rolling, and annealing), the interfacial layers were deformed in a sawtooth shape by forming deformation bands in the Mg alloy and interfacial layers, which favorably led to dramatic improvement in tensile and interfacial bonding properties. This work presents new applications to multi-functional lightweight alloy sheets requiring excellent formability, surface quality, and corrosion resistance as well as tensile and interfacial bonding properties.

Highlights

In the present strip-cast Mg/Al clad sheet, the solidified microstructure composed of equi-axed dendrites exists in the Mg alloy substrate side (Fig. 2a)
According to the comparison of the temperature distributions of the solid Al and liquid Mg alloys with the solidus temperature of the AZ31 Mg alloy, the solidification occurs sufficiently in the border region of the Mg melt pool, i.e., the region which the solid Al or liquid Mg alloy is contacted to the roll surface, whereas it does not occur in the center region of the Mg melt pool at the distance of 30 mm or larger
The very thin layers composed of γand βphases are located along the Mg/Al interface (Fig. 2b,c) because the diffusion bonding time may not be sufficient during the strip casting, which results in the poor interfacial peeling strength (3.2 N/mm) (Table 1)

Summary

Introduction

In the present strip-cast Mg/Al clad sheet, the solidified microstructure composed of equi-axed dendrites exists in the Mg alloy substrate side (Fig. 2a). The very thin layers composed of γand βphases are located along the Mg/Al interface (Fig. 2b,c) because the diffusion bonding time may not be sufficient during the strip casting, which results in the poor interfacial peeling strength (3.2 N/mm) (Table 1).

Results

Conclusion