Nature of creep deformation in nanocrystalline cupronickel alloy: A Molecular Dynamics study

Abstract

Creep resistance and fracture tolerance are considered two essential aspects to look at for material selection and optimization in high-temperature applications. Materials with extensive industrial applications must inherit adequate immune against creep such that operating temperatures can be raised to maximize performance ensuring a long service life of the equipment. The creep study of cupronickel (CuNi) alloy has become crucial because cupronickel alloys are enticing candidates for high-temperature applications. Nevertheless, the fundamental understanding of creep deformation in cupronickel alloys is still obscure. Herein, we executed classical Molecular Dynamics (MD) simulations to reveal the nature of creep characteristics of cupronickel alloy at a molecular level. In particular, we investigated the thermal and mechanical properties of nanocrystalline (NC) Cu, Ni, and Cu0.5Ni0.5 alloy. As the Cu content in the alloy is raised from 0 to 100%, the steady-state creep rate (SSCR) exhibits a ∼12% increment. Based on our MD simulations, we found that the SSCR of Cu0.5Ni0.5 alloy speeds up dramatically under elevated stress, temperature, and decreasing grain size. Our MD results also reveal that at low stress, the governing creep process is the confluence of lattice diffusion, grain boundary diffusion, and grain boundary sliding, while at high stress, the governing creep mechanism turns into dislocation dominated. Admittedly, our computational analysis will help acquire fundamental insights into the creep mechanism of NC cupronickel alloy, which is crucial for the successful usage of this alloy in corrosive, high stress, and high-temperature applications.

Keywords

• NC Cupronickel
• Molecular dynamics (MD)
• Tensile strength
• Creep
• Steady-state creep rate
• High-temperature applications