PROPERTIES OF BULK <font>Fe</font>–<font>Ni</font>/CNT NANOCOMPOSITES PREPARED BY MECHANICAL MILLING AND SINTERING

The effects of carbon nanotubes (CNTs) on mechanical and tribiological properties of the NiFe /CNT composites prepared by high energy mechanical alloying and hot pressing, were investigated. Bulk samples were prepared by sintering of cold pressed (300 MPa) samples at 1040° C for 1 h. X-ray diffraction (XRD) analysis, scanning electron microscopy (SEM) and optical microscopy were employed for evaluation of the phase composition, surface morphology and porosities of the samples. The microhardness of as-milled Ni 3 Fe and NiFe powders reached to 720 and 650 VHN, respectively. The hardness of NiFe and Ni 3 Fe bulk samples reduced to 190 and 270 Vickers because of the grain growth during sintering and remaining porosity. The hardness of NiFe -CNT and Ni 3 Fe -CNT bulk samples reached to 360 and 400 Vickers, respectively. The friction and wear properties of the bulk samples were investigated under dry conditions using a pin-on-disk test rig under an applied load of 8 N. The wear rate, mass loss and friction coefficient of the composite samples remarkably reduced in comparison with NiFe and Ni 3 Fe matrix alloys which demonstrate effects of the CNTs on mechanical and tribiological behavior of the composites resulting from the excellent mechanical properties and unique topological structure of the CNTs.