Optimization of ultrasonic vibration assisted friction stir process to improve mechanical properties of AA7075-nano B₄C surface composite

Abstract

Ultrasonic Vibration assisted Friction Stir Processing is one of the advanced surface modification techniques developed for ductile materials like aluminium to improve their surface properties. The present study is aimed to improve mechanical properties of the AA7075-T651 surface composite by reinforcing the nano B4C particles with optimum working condition. Experiments are conducted at different levels of tool rotation speed, tool processing speed and volume percentage of nano B4C particles with and without ultrasonic vibrations and the experimental results for ultimate tensile strength, impact strength, yield strength, percentage of elongation and hardness are measured. Jaya Algorithm (JA) is used and found best optimum condition such as 1112 r/min of tool rotational speed, 43.96 mm/min of tool traverse speed and 4.02 vol % of B4C nano particles. Mechanical properties and microstructure are investigated using optical Microscope, Field emission scanning electron microscope and Transmission electron microscopy analysis. A fine grain structure and uniform distribution of reinforcement are found in the matrix with the ultrasonic vibrations and the mechanical properties of the AA7075 alloy are improved. The microstructure of the surface composite is correlated with the mechanical properties.