Characterization of pulse electric current sintered Ti-6Al-4V ternary composites: Role of YSZ-Si3N4 ceramics addition on structural modification and hydrogen desorption

In this study, we fabricated Ti-6Al-4V composites using pulse electric current (spark plasma) sintering technique and examined the influence of yttria-stabilized zirconia (YSZ) and silicon nitride (Si3N4) particles on microstructural, mechanical properties. Moreover, we investigated the effects of YSZ and Si3N4 on hydrogen uptake rate of the fabricated composites. The formation of new phases in addition to the parent α and β phases corroborates the increased hardness property exhibited by the Ti-6Al-4V composites. Further, the improvement in the hardness property was ascribed to Orowan strengthening effect due to resistance offered by cross dislocation pinning effect of closely packed particles. From the nanomechanical test, the penetration depth of the unreinforced Ti-6Al-4V alloy was maximum at a value of 272.57 nm, while all the reinforced alloys exhibited reduced penetration depth, thereby increasing the stiffness and strength of the Ti-6Al-4V composites. Other nanomechanical analyses such as nanohardness, elastic modulus, and creep were also improved in the reinforced composites in comparison with the Ti-6Al-4V alloy. The amount of hydrogen absorbed by the specimens was measured, and the Ti-6Al-4V composite with the highest proportion of Si3N4 reinforcement exhibited the highest hydrogen concentration.