Mirostructure and microhardness of aluminum-copper composite reinforced with multi-walled carbon nanotubes prepared by vacuum sintering and hot isostatic pressing techniques

In this study, we report the processing, microstructure, and microhardness of aluminum-copper composites reinforced with multi-walled carbon nanotubes (CNTs). Composite powders were prepared by a high energy ball (HEB) milling process then consolidated by vacuum sintering and hot isostatic pressing (HIP) techniques. The specimens show a uniform dispersion of CNTs in the Al–Cu matrix with CNT content up to 1 wt.% and a cluster formation observed with higher CNT content of 1.5 wt.%. The specimens have a relative density of 92 % to 95 % for composites sintered by vacuum sintering and 93 % to 96 % for composites sintered by HIP. Microhardness of specimens increases with increasing CNT content up to 1 wt% and then decreases due to the formation of CNT clusters. Microhardness is enhanced both by the dispersion strengthening effect of CNTs and by precipitation hardening of Al-Cu matrix.