Microstructural Observation on the Bond Interface in A3003/SUS304L Clad Material

—Characteristics of the Bonded Zone in A3003/SUS304L Clad Material Produced Using Vacuum Roll Bonding(Report 1)—

Abstract

The relationship between bonding conditions and bond strength was investigated for A3003/SUS304L clad material produced using vacuum roll bonding, with observation and analysis of the bond interface conducted by means of a transmission electron microscope, and consideration of the bonding mechanism.
An amorphous phase of 2–5 nm thick was observed on the A3003 side of the bond interface, as well as patch structures. These structures are thought to have been formed due to the fusion and rapid freezing of the bond interface during the roll bonding process.
The direct bonding mechanism of A3003 and SUS304L in vacuum roll bonding is considered to be as follows. Due to friction heat generated during the roll bonding process, an ultra-thin layer (2–5 nm) on the A3003 bond surface fuses with high concentration regions of Cu and Si in the A3003 material. At this time, structural constituents of SUS304L diffuse into the molten layer, thus forming the amorphous layer and patch structures as a result of rapid freezing. This leads to strong bonding between A3003 and SUS304L.