Microstructure and mechanical properties of aluminium-graphene composite powders produced by mechanical milling

Abstract

Graphene has been reported to be a promising nanofiller in fabricating advanced metal matrix composites.

Graphene nanosheets (GNSs) have been incorporated into an aluminium matrix composite using mechanical milling and hot pressing in the current study.

The SEM observation shows that aluminium particles are firstly flattened into flakes, and then fractured/ rewelded into equiaxed particles as the ball milling progresses. The crystalline size is decreased and the lattice strain is increased during the ball milling, which are also intensified by the added GNSs. The hardness of the composite is increased by 115.1% with the incorporation of 1.0 vol. % GNSs.

The local stress induced by the hard GNSs accelerates the milling process. The X-Ray diffraction patterns show that the intensity ratio of (111) to (200) can reflect the preferred orientation of the particle mixture, and the evolution of I(111)/I(200) agrees well with the observed results using SEM. The increased hardness is mainly attributed to the refined microstructure and Orowan strengthening.