Effects of the Sintering Conditions on the Mechanical Properties of Titanium-Carbide-Particle-Reinforced Magnesium Nanocomposites Fabricated by Mechanical Alloying/Mechanical Milling/Spark Plasma Sintering

To enhance the mechanical properties of Mg alloys, we have fabricated Mg/TiC composites by reinforcing the Mg matrix composed of nanosize crystal grains with 20 vol% TiC nanoparticles. The Mg/TiC nanocomposites were fabricated by mechanical milling (MM) and spark plasma sintering (SPS). The TiC nanoparticles were produced by mechanical alloying (MA). The effects of the applied pressure and holding time during SPS on the mechanical properties of this nanocomposite were investigated. Microstructure observations and elemental analysis show that the TiC particles (TiCp) in the nanocomposites have an ultrafine microstructure with an average particle size of approximately 9 nm and they aggregate within the Mg matrix. The Vickers hardness of the nanocomposites increases to 150 HV when the SPS applied pressure and holding time are increased. However, the increase in the hardness is accompanied by a decrease in the bending strength. The main factors for the improvement of the mechanical properties of the 20 vol% TiCp/Mg nanocomposite are considered to be the density and compressive residual stress.