Electro-thermal and mechanical property analysis of powder metallurgy processed, multi-stage ball milled aluminium-copper-multi walled carbon nanotube composite

Abstract Aluminium Metal Matrix Composite (Al-MMC) is a favourable option for industries like automotive, aerospace, sports equipment, electronic packaging and renewable energy because of its impressive strength-to-weight ratio, effective thermal and electrical conductivity, abundant availability and reasonable cost of aluminium. Carbon nanotube (CNT) reinforced Al-MMC is popular among researchers due to its impressive strength and stiffness. The electrical and thermal conductivity of Al-CNT is a less focused field with challenges like uniform dispersion and structural integrity of CNT depending on the manufacturing process. In this paper, a novel method of Multistage ball milling (MSBM) was introduced to develop a powder metallurgy processed Al-MMC, consisting of 5-weight percentage (5 wt%) of copper (Cu) and 0.5 to 1.5 volume percentage (0.5–1.5 vol%) multi-walled carbon nanotubes (MWCNT). In MSBM, mixing was done in two stages with two different rpms of the ball mill to add the advantages of flake powder metallurgy with lower chances of structural damage and the agglomeration of CNT. Mechanical, electrical, thermal, and microstructure characteristics of the fixed-speed single-stage ball milling (SSBM) process and the MSBM were compared. MSBM-processed Al-5Cu-0.5CNT composites showed higher electrical conductivity (15.03%), thermal conductivity (5.88%) and hardness (9.68%) than SSBM-processed composites. Al-5Cu-0.5CNT developed by the MSBM process achieved superior electrical and thermal conductivity, surpassing pure sintered Al by 138.45% and 9.39%, respectively.