Fabrication of Friction Stir Processed Al-Ni Particulate Composite and Its Impression Creep Behaviour

Abstract

Nickel powders were troweled on roughened Al base plate using a friction tool made from tool steel. Friction stir processing (FSP) was carried out using a load of 8 kN and with a tool rotation speed of 800 rpm and thus a surface composite was processed. Processed samples were characterized for revealing the microstructural features. SEM and XRD analysis revealed the presence of fine Ni particles in the stir zone which lead to a significant increase in hardness. Using the “refined energy model,” the maximum temperature developed within the processed zone was estimated and found to be around 275°C. Impression creep behaviour was assessed on both the base metal and processed zone at the temperature of 30, 100, and 200°C. Creep curves were generated and steady state creep rate (SSCR) values were found out to determine the activation energy. It is observed that friction stirred regions record higher creep rate values compared to the base metal. Estimated activation energy is in the range of 6 to 16 kJ/mol. Activation energy is marginally lower in the base metal compared to friction stir processed region.