INVESTIGATION OF POWDER METALLURGY TITANIUM MATRIX COMPOSITES BY PLANETARY BALL-MILLING OF TI POWDER DISPERSED WITH VAPOUR GROWN CARBON NANOFIBERS

摘要

Planetary ball milling was employed to disperse 0.4～1.0 wt% vapour grown carbon nanofibers (VGCFs) with pure Ti powder. The powder mixtures were consolidated at 1073 K by spark plasma sintering. Hot extrusion was performed at 1273 K with an extrusion ratio of 37:1. The mechanical properties of the extruded titanium matrix composites were investigated to evaluate the strengthening effects of the VGCFs additives. The extruded Ti-VGCF composites, with a 1.0 wt% VGCF additives dispersed by PBM, exhibited an excellent tensile strength of 1182 MPa in 0.2%YS and 1179 MPa in UTS, which demonstrated a 143.6% and 80.7% increase compared to that of the extruded pure Ti. The improvement of strength was elucidated as contribution of the grain refinements, dispersion strengthening of the in-situ formed TiC particles and VGCFs, as well as a solid solution strengthening of the carbon, oxygen and nitrogen in the Ti matrix.