Magnesium-based nanocomposites:A review from mechanical,creep and fatigue properties

The addition of nanoscale additions to magnesium(Mg)based alloys can boost mechanical characteristics without noticeably decreasing ductility.Since Mg is the lightest structural material,the Mg-based nanocomposites(NCs)with improved mechanical properties are appealing materials for lightweight structural applications.In contrast to conventional Mg-based composites,the incorporation of nano-sized reinforcing particles noticeably boosts the strength of Mg-based nanocomposites without significantly reducing the formability.The present article reviews Mg-based metal matrix nanocomposites(MMNCs)with metallic and ceramic additions,fabricated via both solid-based(sintering and powder metallurgy)and liquid-based(disintegrated melt deposition)technologies.It also reviews strengthening models and mechanisms that have been proposed to explain the improved mechanical characteristics of Mg-based alloys and nanocomposites.Further,synergistic strengthening mecha-nisms in Mg matrix nanocomposites and the dominant equations for quantitatively predicting mechanical properties are provided.Furthermore,this study offers an overview of the creep and fatigue behavior of Mg-based alloys and nanocomposites using both traditional(uniaxial)and depth-sensing indentation techniques.The potential applications of magnesium-based alloys and nanocomposites are also surveyed.

Use of carbon nanotubes for strain and damage sensing of epoxy-based composites

The interest in structural health monitoring of carbon fiber-reinforced polymers using electrical methods to detect damage in structures is growing because once the material is fabricated the evaluation of strain and damage is simple and feasible.In order to obtain the conductivity,the polymer matrix must be conductive and the use of nanoreinforcement seems to be the most feasible method.In this work,the behavior of nanoreinforced polymer with carbon nanotubes(CNTs)and composites with glass and carbon fibers with nanoreinforced matrices was investigated.These composites were evaluated in tensile tests by simultaneously measuring stress,strain and resistivity.During elastic deformation,a linear increase in resistance was observed and during fracture of the composite fibers,stronger and discontinuous changes in the resistivity were observed.Among other factors,the percentage of nanotubes incorporated in the matrix turned out to be an important factor in the sensitivity of the method.