The effect of nano-void on deformation behaviour of Al-Cu intermetallic thin film compounds

Computational Materials Engineering Group, Department of Metallurgical and Materials Engineering, National Institute of Technology, Rourkela, 769008 Odisha, India
e-mail: pals@nitrkl.ac.in

Received: 31 March 2015
Accepted: 31 August 2015

Abstract

In the present study, deformation behaviour of AlCu, Al₂Cu₃ intermetallic thin films having a nano-void at its center have been investigated using molecular dynamics (MD) simulation. The results are compared with the thin films of pure Al, Cu metals and intermetallic AlCu, Al₂Cu₃ thin films having no defect for estimating the effect of nano-void on the mechanical properties of intermetallic thin film. Simulated tensile tests are performed at different strain rates (10⁸ s^-1, 0.5 × 10⁹ s^-1 and 10⁹ s^-1) and temperatures (10 K, 50 K and 300 K). All the stress-strain curves have zig-zag nature after initial linear elastic portion, which quite resembles with the typical nano-scale material behavior. Al₂Cu₃ intermetallic thin film exhibits higher yield strength compared to AlCu intermetallic thin film. The atomic configurations captured during deformation clearly show that deformation is localized near the void, followed by void closure and necking of the thin film. The failure of thin film occurs after straining down to a point indicating its ductile nature. An increase in the magnitude of average stress near the void has been revealed from Von Mises’ stress analysis on the defect surface. The stress around void is increased uptill the attainment of maximum stress. The strain is localized near the void, which actually helps in breaking of the atomic bonds and ultimately causes fracture.