Morphology Of Primary Mg Research Articles

Investigation on morphology of primary Mg2Si in Al-20wt.%Mg2Si composite with experiment and first-principle calculations

The morphology of refined primary Mg 2 Si always exhibits the faceted crystal growing pattern in the Al-Mg 2 Si composites. The 2D and 3D morphologies of primary Mg 2 Si particles were examined by scanning electron microscopy (SEM) and field emission scanning electron microscope (FE-SEM) respectively. The morphology evolution mechanism of the faceted primary Mg 2 Si in Al-Mg 2 Si composite was investigated. The results show that there were only (100) planes and (111) planes emerging in Mg 2 Si particles. The morphology evolution of faceted Mg 2 Si has only two growing paths including Cube to Truncated Cube and Octahedron to Truncated Octahedron. The morphology evolution, critical nucleus and growth, was determined by r value which was deduced from the ratio of the surface free energy of (100) planes to the surface free energy of (111) planes. The surface free energies were identified by First-principle simulation. The validity of the above two growing path modes were verified. The configurations of the surface elements in faceted Mg 2 Si particles are predicted according to the simulating results. • Three-dimensional morphology of faceted primary Mg 2 Si in Al-20%Mg 2 Si composite was investigated in detail. • Nucleation and growth mechanism of faceted primary Mg 2 Si were proposed in the work. • Prediction of the outer atoms in different Mg 2 Si morphology was proved by First-principle simulation.

Effect of Mn addition on the microstructure and tensile properties of Al–15%Mg2Si composite

Abstract This research was carried out to investigate the influence of different concentrations of Mn (0.5, 1, 2, 3 and 5%) on the microstructure and tensile properties of Al–15 wt.%Mg 2 Si metal matrix composite. Microstructural examination was carried out using optical and scanning electron microscopy (SEM). The results depicted that 1 wt.% Mn addition changes the morphology of primary Mg 2 Si from irregular to polyhedral shape and its average particle size decreases from 40 μm to 12 μm. Cubic morphology of particles was also observed by the addition of 2% Mn. Further addition of Mn (>2%) did not significantly change the size or morphology of the primary Mg 2 Si. Microstructural studies also showed that Mn addition changes the morphology of the eutectic Mg 2 Si phase from flake-like to rod-like. Tensile properties of specimens with different Mn contents were also investigated. The results of tensile testing revealed that optimum Mn level for improving both UTS and elongation values is 2 wt.%. At higher Mn concentrations, an intermetallic phase (Al 6 Mn) introduced on eutectic cell boundaries appears to be the main reason for slight reduction in tensile properties. A study of the fracture surfaces via SEM revealed a brittle mode of failure in Mn free composite. However, the addition of 2 wt.% Mn changes the fracture mode to ductile by increasing fine dimples and reducing the number of decohered particles thereby increasing the composite ductility.