Influence of ball milling parameters on the dispersion characteristics and structural integrity of MWCNTs in nickel aluminide matrix powders

The novelty of incorporating carbon nanotubes (CNTs) in various matrices is becoming increasingly significant for the development of various composites to match the rising technological demands in industry. However, for the potentials of CNTs to be fully realized, the mandatory requirement to uniformly disperse them must be achieved. To effectively disperse these nanotubes in metallic matrices, ball milling has emerged as an effective method, but concerns still persist as to the ability of this method to achieve uniform dispersion without significant damage to the CNTs. In this work, multi-walled carbon nanotubes (MWCNTs) were dispersed in a nickel aluminide matrix via three different milling methods, using both low and high energy milling regimes. The admixed powders were characterized using X-ray diffraction, Raman spectroscopy, scanning electron microscopy, energy-dispersive X-ray spectrometry and transmission electron microscopy techniques. Results show that a two-stage milling, comprised of a 6-h low energy milling with a short-term follow-up of a low speed 2-h high energy milling achieved the best MWCNTs dispersion and retained their structural integrity.