Effect of Nano-Silica Volume Reinforcement on the Microstructure, Mechanical, Phase Distribution and Electrochemical Behavior of Pre-Alloyed Titanium-Nickel (Ti-Ni) Powder

Abstract

Titanium-Nickel pre-alloyed powder was reinforced with Nano-Silica in 2%, 4% , 6% and 8 wt. % due to effectiveness of Nanoscale ceramic Reinforcement in improving the properties of Metals and Alloys. The compositions of the Pre-Alloyed powders and Nano Silica Approximately 50 nm in diameter and spherical in shape were weighed and mixed in Planetary Ball Mill followed by compaction at 50 MPa using a Uniaxial Compaction machine The green pellets obtained were sintered in Argon Environment for 5 hrs and allowed to furnace cool. The pellets were then sectioned through their cross-section for slices 3 mm thick followed by Cold-mounting and Soldering followed by cold mounting additionally. The Samples were analyzed via X-Ray Diffraction (XRD) for phase distribution as a function of variation in nano-Silica reinforcements and Microstructural analysis was performed via Optical Microscope. The effect of Volume percentage on the densification was determined via Archimedes principle and Micro-Vickers hardness was used for mechanical Evaluation. The Electrochemical Properties were evaluated using Potentio-Dynamic Polarization and Electrochemical Impedance Spectroscopy (EIS) in neutral salt solution (3.5% NaCl). The results indicated increasing dissolution of the TiNi phase into intermetallic Titanium-rich and Ni-rich phases in the matrix and hardening due to the Nano-Silica effect of Grain Boundary impingement and phase dissolution of Equiatomic phase and mixed behavior in Corrosion properties as determined by the electrochemical techniques whereas densification decreased due to poor plasticity of Nano-Silica and hinderance in diffusion during the sintering process.