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T3.10.1

First-Principles Study of Mechanical Properties of Alumina-Copper Nano-Coating Interfaces Shingo Tanaka1, Rui Yang2 and Masanori Kohyama1 1 Research Institute for Ubiquitous Energy Devices, National Institute of Advanced Industrial Science and Technology (AIST), Ikeda, Osaka 563-8577, Japan. 2 Department of Computer Science, Faculty of Engineering and Information Technology Australian National University, Canberra, ACT 0200, Australia. ABSTRACT Mechanical properties of alumina-copper nano-coating interfaces have been studied by the first-principles calculations. We have applied the rigid-type first-principles tensile tests for O-rich (O-terminated) and stoichiometric (Al-terminated) interfaces and for back Cu1st-Cu2nd interlayers. The O-terminated interface is twice as strong as the Cu1st-Cu2nd interlayer whereas the Alterminated interface is twice as weak as the Cu1st-Cu2nd interlayer. We have performed the fitting of interlayer potentials by universal binding-energy relation (UBER). The interlayer potential of the Cu-Al interface is well reproduced by UBER in whole region, although those of Cu-O interface and Cu1st-Cu2nd interlayer are partially reproduced. INTRODUCTION Mechanical properties of nano-coating interfaces as ceramics/metal interfaces [1-9] are of great importance. In order to develop the high performance materials, it is desirable to understand the mechanical properties of such interfaces at the atomic and electronic level. Alumina-copper nano-coating interfaces are typical ceramics-metal systems frequently used in mechanical and electronic applications. Recently, we have performed the first-principles calculations of the O-rich (O-terminated) and stoichiometric (Al-terminated) interfaces using a pseudopotential method and the first-principles molecular dynamics [10,11]. The stable atomic configuration of the O-terminated interface is in good agreement with the recent HRTEM observation [10,12]. The O-terminated interface has a strong covalent and ionic bonding, whereas the Al-terminated interface has a weak metallic bonding with partially covalent character. The O-terminated interface is about five times as large as the Cu adhesive energy of the Al-terminated one [6,9-11]. These interfaces have quite different characters to each other. The first-principles tensile test (FPTT) is a powerful method for an investigation of the interface mechanical and electronic properties in atomic scale. In a rigid-type FPTT, we can select cleavage planes for the relaxed configuration, and the changes in the energy and electronic structure are examined for the rigid cleavage between selected planes. The interlayer potential can be directly obtained from rigid FPTT. In this paper, we estimate an ideal tensile strength near the interface and an interface Young’s modulus of alumina-copper system from interlayer potential curves. Universal binding-energy relation (UBER) analyses [13,14] have succeeded in explaining the atomic potential curves for simple covalent or metallic bonding nature. We perform the UBER fitt