Microstructural and mechanical characterization of Al–15%Mg2Si composite containing chromium

The microstructure and mechanical properties of Al–15%Mg2Si composite containing different Cr contents (0.5 wt.%–5 wt.%) were studied. Scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) analysis were utilized to study the microstructures and fracture surfaces of the composite. The results revealed that the addition of Cr contents changes the size and morphology of both primary and eutectic Mg2Si phases. A new intermetallic compound (Al13Cr4Si4) was detected through the microstructural studies at higher Cr levels. Adding Cr also made significant raise in the hardness, ultimate tensile strength (UTS) and elongation values of the composite. A slight reduction in tensile properties was seen at high Cr concentrations (>2 wt.% Cr). The study of fracture surfaces of the Al–15%Mg2Si–2%Cr composite revealed the presence of less broken particles and more fine dimples.

► Effect of Cr on the microstructure and mechanical properties of Al–Mg2Si composite.
► Cr changed pseudoeutectic Mg2Si morphology from flake-like to rod-like.
► Higher hardness, elongation and UTS values obtained from Cr-containing specimens.
► Presence of Cr-containing intermetallics at higher Cr contents (>1 wt.% Cr).
► Cr addition changed the mode of fracture from brittle to ductile.