A Novel Method to Fabricate CNT/Mg-6Zn Composites with High Strengthening Efficiency

doi:10.1007/s40195-014-0144-1

Abstract

Abstract:

A novel method was developed to fabricate carbon nanotubes (CNTs)-reinforced Mg matrix composites. The method consists of two steps: CNTs pre-dispersion by ball-milling and the ultrasonic melt processing. Mechanical ball-milling effectively pre-dispersed CNTs on Zn flakes with suitable rotational speed and ball-milling time. Serious CNT entanglements were dispersed by the ball-milling. However, ball-milling for a long time at high speed would damage the morphology of CNTs. The ultrasonic overcame the poor wettability between Mg melt and CNTs and then dispersed pre-dispersed CNTs in the Mg melt. CNTs were distributed well in the composites and maintained integrated structure. CNTs significantly improved the mechanical properties of the matrix. The strengthening efficiency reached to 37.1, which proves the superiority of this novel method. Besides grain refinement, load transfer may make a great contribution to the improvement of the strength for the composites.

Key words: Pre-dispersion, Carbon nanotubes, Magnesium matrix composites, Mechanical properties, Ultrasonic vibration

Shi Hailong, Wang Xiaojun, Li Chendong, Hu Xiaoshi, Ding Chao, Wu Kun, Huang Yudong. A Novel Method to Fabricate CNT/Mg-6Zn Composites with High Strengthening Efficiency[J]. Acta Metallurgica Sinica (English Letters), 2014, 27(5): 909-917.

Figures/Tables 11

Fig. 1 Temperature-time flow chart of the composites fabricating

Fig. 2 Morphology of the raw CNTs: a low-magnification image; b high-magnification image

Fig. 3 SEM images showing the CNT distribution on Zn flakes after ball-milling at 200 r/min for 1 h a, 4 h b, 8 h c, 10 h d

Fig. 4 SEM images showing the CNTs distribution on Zn flakes after ball-milling at 300 r/min for 1 h a, 4 h b, 8 h c, 10 h d

Fig. 5 SEM images showing the CNTs distribution on Zn flakes after ball-milling at 400 r/min for 1 h a, 4 h b, 8 h c, 10 h d

Fig. 6 Photographs of CNT/Zn precursor compacts

Fig. 7 SEM images of as-cast CNT/Mg-6Zn composite: a low-magnification image; b high-magnification image

Fig. 8 TEM images of CNT/Mg-6Zn composite: a low-magnification image; b high-magnification image

Fig. 9 Typical stress-strain curves of as-cast Mg alloy and CNT/Mg-6Zn composite

Fig. 10 Optical images of as-cast Mg-6Zn alloy a CNT/Mg-6Zn composite b

Fig. 11 SEM images of the fracture surfaces of CNT/Mg-6Zn composite (a) high magnification. (b) lower magnification

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