Fabrication of MWCNTs reinforced iron metal matrix composite by powder metallurgy: Effects of wet and dry milling

Abstract

The present paper reports the effects of wet and dry milling on the phase transformation, microstructure evolution and mechanical properties during fabrication of iron based composite reinforced with 21 vol% MWCNTs (multi-walled carbon nanotubes) by using high energy planetary milling followed by pressureless conventional sintering. A powder mixture containing Fe-21 vol% MWCNTs is milled in both wet (toluene) and dry (argon atmosphere) condition for 12 h in a dual drive planetary mill. The change in particle size, morphology, evolution of phases and also dispersion of MWCNTs into iron matrix during wet and dry milling are highlighted. It has been observed that wet milled powders are fine (average size d50 = 10 µm) and exhibit narrow size distribution whereas dry milled powders (average size d50 = 90 µm) show wide range binomial distribution. The maximum hardness of 450 VHN and compressive strength of 525 MPa are achieved for the wet milled composite powders sintered at 1300 °C for 2 h.