Microstructure, mechanical and thermal properties of CNTs/Mg-9Al composites

Abstract

The effect of carbon nanotubes (CNTs) on the aging behavior of Mg-9Al matrix composites was studied, and the evolution of microstructures, mechanical properties and thermal conductivity of composites during the aging treatment were discussed. Results show that the addition of CNTs increases the solid solubility of Al in Mg matrix and limited the migration of grain boundaries during the aging process, which can promote the formation of continuous precipitated phases β-Mg17Al12 in CNTs/Mg-9Al composites. The rod-shaped continuous precipitates in coherent relationship with Mg matrix can effectively hinder the dislocation movement, which can improve the mechanical properties of the composites. Besides, the reduction of solid solution Al atoms during aging process and the addition of CNTs can improve the thermal conductivity of the composites. The property evaluation indicates that the tensile yield strength, ultimate tensile strength, diffusivity and thermal conductivity of peak-aged 0.4CNTs/Mg-9Al composite are 275 MPa, 369 MPa, 34.5 mm2/s and 68.4 W/(m·K) respectively, showing 17%, 23%, 43% and 45% increasing in comparison with those of Mg-9Al before aging.

Keywords

• cnts
• magnesium matrix composites
• aging treatment
• mechanical property
• thermal conductivity