Abstract
Ti-6Al-4V alloys are well known for their high strength to weight ratio, corrosion resistance, fatigue and high temperature properties. In this Study, the effect of TiN addition on the mechanical properties of spark plasma sintered Ti-6Al-4V alloys was investigated. Ti-6Al-4V alloy powders with different proportions of TiN (2, 4 and 6%) were produced using Spark Plasma Sintering (SPS). Further, the spark plasma sintered samples were analysed using scanning electron microscopy, X-ray diffraction and optical microscope. The spark plasma sintered samples were then investigated for mechanical behaviours such as creep, erosion-wear and wear response. Creep, modulus of elasticity and hardness properties were investigated using the nanoindentation technique equipped with Berkovich indenter. On the other hand, high velocity solid particle erosion test was used to examine the erosion-wear behavior of Ti-6Al4V alloy with and without TiN additions. The aim and objectives of the research was to understand how different proportions of TiN addition affect the creep and erosion wear response of Ti-6Al-4V-TiN composite, investigate the mechanisms of creep on the using nanoindentation test, and evaluate the mechanism of wear occurring on the nano-composites and to characterize and analyse surface morphologies and fracture mode of SPS Ti6Al-4V-TiN composites. The results revealed that the use of SPS technique and TiN nanoparticles has led to transformation from alpha/beta lamellar to bimodal microstructure. It was also noticed that the presence of TiN improves the mechanical properties of Ti-6Al-4V to some extend and lead to deterioration as the volume fraction of TiN goes to 4% volume fraction. Nanoindentation results revealed that elastic modulus and hardness increased drastically with increase in TiN addition. Increasing the applied load reduced the hardness and elastic modulus. Ti-6Al-4V+ 6% TiN presented improved mechanical properties such as erosion wear, abrasive wear and creep resistance.
M.Eng. (Engineering Metallurgy)