Thermomechanical Processing and Roll Bonding of Tri-Layered Cu-Ni-Zn/Cu-Cr/Cu-Ni-Zn Composite
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INTRODUCTION
HYBRID or clad layered composites manufactured by joining different materials can be considered as the stratified composite developed for the purpose of improving the mechanical,[1,2] electrical,[3,4], and chemical properties.[5,6] The properties of layered composite materials are determined by the selection of component materials to be joined[3] and the stacking structure of different materials with various thicknesses and interface structure and properties.[3] Joining various materials can be achieved by the shear deformation on the contact surface induced by shear stress,[3,7–9] by mechanochemical reaction[5] and/or by atomic diffusion/interface reaction induced by thermal activation.[2] In order to enhance the reliability of interface in layered composite materials, both mechanical and thermal bonding between dissimilar materials should be optimized.[3,10,11] One of the most efficient and cost-competitive methods to produce layered composite materials is the roll-bonding process.[7–9,12] In order to maintain excellent bonding at the interface between dissimilar materials in hybrid or clad metals, the interfacial defects such as voids and/or brittle intermetallics should be strictly controlled.[3,5] The weak or brittle interface between layers of materials usually
HOBYUNG KIM and GYEONG TAE KANG, Graduate Students, and SUN IG HONG, Professor, are with the Department of Nanomaterials Engineering, Chungnam National University, Daejeon 305-764, Korea. Contact e-mail: [email protected] Manuscript submitted May 6, 2015. METALLURGICAL AND MATERIALS TRANSACTIONS A
results from the presence of un-bonded interface, voids and thick brittle intermetallic layers at the joint interface.[3,5,8,12] The voids are likely to be associated with weak mechanical force or unbalanced diffusion while the brittle intermetallic layers are formed by the excessive interfacial thermo-chemical reaction.[5] Joining or roll-bonding chemically similar alloys with physically dissimilar properties has some advantages over joining chemically dissimilar metals because combinations of excellent material properties can be exploited with little trouble associated with chemical reaction at the joining interface. One of the most important advantages is the good bondability with the absence of brittle intermetallic layers which are detrimental to the interface strength and mechanical reliability. Cu-Ni-Zn alloy is a mainly solution strengthening alloy while Cu-Cr alloy is a precipitation strengthening alloy. Cu-Ni-Zn-based alloys have a combination of properties such as good corrosion and abrasion resistance, and acceptable mechanical properties as reported by Song and Hong.[13] Precipitation strengthening Cu-Cr possesses the high electrical conductivity coupled with excellent strength, making them ideal for electrical/electronic component materials. Cu-Ni-Zn/Cu-Cr combination is interesting because the strength of Cu-Cr can be varied by aging treatment. Roll-bonded Cu-Ni-Zn/Cu-Cr/Cu-Ni-Zn composite can be strengthened during roll-bonding and/o
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