Effect of ball-milling time on mechanical and magnetic properties of carbon nanotube reinforced FeCo alloy composites

摘要

Abstract Carbon nanotubes (CNTs) reinforced FeCo alloys were produced by high energy ball-milling and spark plasma sintering (SPS). CNTs distribution in the FeCo alloy was gradually improved as ball-milling time increased, with a uniform dispersion achieved after 6h ball-milling. Tensile tests demonstrated that, as the ball-milling time increased, the yield strength increased in the composites; a maximum 50% relative increase in tensile strength due to the addition of CNTs was achieved after 1h ball-milling, which then decreased with further ball-milling. The elongation to fracture was significantly increased after 1h ball-milling and then decreased with further ball-milling. SEM results show a patch of dimples in the fracture surface of the composite, indicating improved ductility due to CNTs. The coercivity was increased with increased ball-milling time, while the saturation induction showed a peak value after 1h of ball-milling and then decreased with further ball-milling. Raman spectra of the composite indicated that no serious damage had been imparted to the CNTs during ball-milling. Graphical abstract Display Omitted Highlights • Dispersion CNTs in FeCo alloy by ball-milling improves ultimate strength, yield strength and elongation of inherent brittle FeCo alloy. • In ordered to achieve the best combination between magnetic and mechanical properties, the ball milling time must be 1h at ball to powder ratio~6:1. • Uniform dispersion of CNTs was achieved after 6h ball milling. However, carbides were formed in microstructure.