Papers by Keyword: Mg Matrix Composites

Abstract: A wet powder metallurgy (WPM) process was developed to disperse carbon nanotubes (CNTs), and to fabricate the CNTs reinforced Mg matrix (CNTs/Mg) composite. The dispersion effect of CNTs were evaluated by field emission scanning electron microscopy (FE-SEM), dynamic light scattering (DLS) and high-resolution transmission electron microscopy (HR-TEM), respectively. Results showed that the CNTs were homogeneously dispersed on the surface of Mg powder. Adequate bonding and good interfacial interaction between the CNTs and Mg matrix contributed to the efficient load transferring from the CNTs to Mg matrix under a mechanical force. Furthermore, no brittle MgO was formed on the surface and it was beneficial to improving the adhesion of the CNTs to Mg matrix. With 0.5 wt.% CNTs addition, the CNTs/Mg composite experienced remarkable enhancements in tensile stress of 28% and Young’s modulus of 24%. The reasons responsible for these enhancements are suggested as the effective dispersion of the CNTs and the good interface bonding between the CNTs and Mg matrix.

Abstract: Mg alloy is the lightest material of structural materials and is noticed for lightweight automotive parts because of excellent castability and damping capacity compared with Al alloy. But Mg alloy has poor corrosion resistance and high temperature creep properties. In this study, Mg matrix composites were fabricated by squeeze casting method to improve high temperature creep properties and damping capacity. The creep properties and damping capacity of hybrid Mg composites reinforced with Alborex(Aluminum borate whisker: 9(Al2O3)•2(B2O3)), graphite particle, and carbon fiber were improved in comparison with Mg alloy. Hybrid Mg composites reinforced with carbon fiber and Alborex were better than those reinforced with graphite particle and Alborex in mechanical properties, creep characteristics, and damping capacity, etc.

Abstract: Mg alloys have potential to use automotive parts because of their weight and castability. High temperature strength and damping capacity is important to the automotive power train parts. Mg alloy has lower creep and thermal fatique strength but has better damping capacity than Al alloy. It is known that short fiber reinforced Mg metal matrix composites(MMC) exhibits superior high temperature strength and graphite reinforced Mg MMC shows excellent damping capacity. Therefore, in this study, the effect of graphite particles(15-25%) and alborex (9Al₂O₃ּ2B₂O₃) whiskers(5-15%) on the damping behavior and mechanical properties of Mg MMC was studied. Graphite particles and alborex whiskers were chosen to increase damping capacity and high temperature strength, respectively. The Mg MMC was fabricated by squeeze casting and the total quantity of reinforcements(graphite + alborex) was maintained to 30 volume percent. The damping capacity of the metal matrix composites was increased and the flexural strength and hardness were decreased with increasing the volume fraction of graphite particles, that is, reducing the volume fraction of alborex whiskers.