Tensile deformation behaviours of polycrystalline Cu80Ni20 alloy: insights from molecular dynamics simulations

The polycrystalline Cu80Ni20 sample was simulated by molecular dynamics (MD) approach. This sample consists of the fcc and hcp crystals alternated with disordered (d-) structures. Under the uniaxial tensile test, the sample exhibits elastic and plastic behaviours. The fcc and hcp crystals disintegrate into the d-structures with increasing strain but small clusters of fcc and hcp crystals still exist at the large strain. A very small number of d-atoms recrystallises into the fcc and hcp crystals during the tensile deformation. The distances between atoms are stretched gradually during the tensile loading. The growth and coalescence of big simplexes with RS ≥ 2.0 Å occur only in the d-structures. The shear band (SB) is formed during the tensile deformation. The big simplexes coalesce and propagate in the SB, causing the crack propagation.