Powder Metallurgy Processes for Composite–Materials Integration

Abstract

Uniform dispersion of unbundled carbon nanotubes (CNTs) was the bottleneck to convert their attractive properties to CNTs-reinforced composites. In this study, a solution ball milling (SBM) approach was developed to homogeneously disperse CNTs in Al matrix composites (AMCs). The process integrated strategies of solution coating, mechanical ball milling, and Al flake producing into a simple organic unity. The dispersion quality, crystal structure, and strengthening effect of CNTs in AMCs processed by SBM were investigated through scanning electron microscopy, transmission electron microscopy, Raman analysis, and tensile tests. Compared with previous methods, the SBM process was simple and effective to obtain a homogeneous CNT dispersion with a large aspect ratio and small CNT damages. The tensile strength of Al matrix was noticeably enhanced by CNT additions agreeing with the potential strengthening effect predicted by the load transfer mechanism. Shortened carbon nanotubes (CNT) were completely transformed to in situ Al₄C₃ nanorods by template reaction of CNT with Al matrix via powder metallurgy. Strong Al–Al₄C₃ interface, good distribution and complete single-crystal structure of Al₄C₃ nanorods, resulted in a remarkably improved strengthening effect in Al matrix composites. It concluded that in situ formed Al₄C₃ nanorod was a novel promising reinforcement for designing high-performance Al nanocomposites.