Microstructure of in situ Mg metal matrix composites based on silica nanoparticles

Metal matrix composites comprising a magnesium matrix and Mg2Si/MgO dispersoids obtained by hot pressing silica nanoparticle agglomerates and metal powder in a Degussa press were characterized. Two powder mixtures having weight proportions of Mg:SiO2 of 10:0.3 and 10:1 were identically sintered. Their microstructures were characterized by optical microscopy and X-ray diffraction. The size and distribution of the Mg2Si and MgO dispersoids formed in situ were assessed as a function of the original nanosilica content. The behaviour of the composites under compression testing was assessed in 3D by X-ray microtomography using 225kV Nikon X-tek and 150kV Xradia MicroXCT scanners. This provided insights into composite strengthening mechanisms and matrix particle decohesion.</jats:p

X-ray microtomography for 3D microstructure characterization of magnesium matrix composite reinforced with glassy carbon particles

The microstructure of novel AZ91 magnesium matrix composite reinforced with glassy carbon particles has been characterized in this study. The composite was produced by hot pressing a mixture of glassy carbon particles and metal powder. Beforehand, the particles were coated with SiO2 by a sol-gel method. Metris X-tek and Xradia MicroXCT laboratory X-ray tomography systems were used to obtain 3D microstructural information (particle-size distribution, volume fraction of particles, phase formation and defects in the form of clusters of particles and pores). These 3D features were validated by 2D scanning electron microscopy (SEM) methods.</jats:p