Microstructure, consolidation, electrochemical, and mechanical performance of titanium (Ti) composites reinforced by graphene nanoplatelets (GNPs) via mechanical alloying

In present work, mechanical alloying (MA) is employed to produce composite powders of titanium (Ti) containing 0.25 wt% graphene nanoplatelets (GNPs). Four composite powder samples are prepared by carrying out high energy ball milling (HEBM) at different milling times. Subsequent cold compaction and pressureless sintering are performed to obtain sintered compacts. Influence of ball milling time on powder characteristics, crystallographic as well as morphological evolution, relative density, compressibility, corrosion rates and mechanism, sinterability and hardness of the composites have been investigated. The plastic deformation capacity and yield stress of the composite powders are analyzed using linear compaction equations. X-ray diffraction has confirmed the non-occurrence of titanium carbide (TiC) formation during MA. Scanning electron microscopy has not only revealed a transformation in morphology of Ti particle from bulk shape to flaky but also has shown a strong adherence of GNPs on Ti particles. Electrochemical characterization results indicate that exchange current density for 6 h ball milled sample is quite high that leads to a thicker TiO2 resulting in pitting corrosion. Sinterability and micro hardness values are found to be highest for 2.5h ball milled composite in comparison to others.