Atomistic Simulation Study of Mechanical Deformation of AI-Mg-Si Alloys

摘要

Aluminum alloys have been attracting significant attention. Especially Al-Mg-Si alloys can exhibit an excellent balance between strength and ductility. Deformation mechanisms and microstructural evolution are still challenging issues. Accordingly, to describe how the type of phase influence mechanical behaviour of Al/Mg/Si alloys, in this paper atomic simulations are performed to investigate the uniaxial compressive behaviour of Al-Mg-Si ternary phases. The compression is at the same strain rate (3.10~(10)s−1); using Modified Embedded Atom Method (MEAM) potential to model the deformation behaviour. From these simulations, we get the total radial distribution function; the stress-strain responses to describe the elastic and plastic behaviors of GP-AlMg_(4)Si_(6), U2-Al_(4)Mg_(4)Si_(4)and β-Al_(3)Mg_(2)Si_(6)phases. For a Detailed description of which phase influence hardness and ductility of these alloys; the mechanical properties are determined and presented. These stress-strain curves obtained show a rapid increase in stress up to a maximum followed by a gradual drop when the specimen fails by ductile fracture. From the results, it was found that GP-AlMg_(4)Si_(6)& U2-Al_(4)Mg_(4)Si_(4)phases are brittle under uniaxial compressive loading while β-Al_(3)Mg_(2)Si_(6)phase is very ductile under the same compressive loading. The engineering stress-strain relationship suggests that β-Al_(3)Mg_(2)Si_(6)phase have high elasticity limit, ability to resist deformation and have the advantage of being highly malleable. Molecular dynamics software LAMMPS was used to simulate and build the Al-Mg-Si ternary system.