Surface modification of aluminum alloy 6061 by embedding B4C particles via friction stir processing

Abstract

Aluminum alloy-based surface composites have been in numerous applications since the introduction of the Friction Stir Processing (FSP) method to develop multifunctional properties owing to its ease of use and control in process parameters to obtain desired properties. AA6061-T651 is used as a substitute for AA6082 in structural applications due to its higher strength in comparison. To further improve the surface properties of AA6061, the friction stir processing technique was employed to reinforce Boron Carbide (B4C) particles by the Blind-Hole method. To achieve uniformity in distribution, FSP with a different direction strategy has been adopted. The surfaces thus developed were characterized using Optical Microscopy (OM) and Scanning Electron Microscopy (SEM) techniques. The grain size measurement was made on the processed samples using Heyn lineal intercept method. Tension and microhardness tests were also conducted to study the change in mechanical properties. The dark carbide zones with clear boundaries were identified in single pass processed specimens. Uniformity in the B4C distribution was observed on the dual-pass surface. In addition, Energy-Dispersive Spectroscopy (EDS)results have shown the presence of B4C embedded regions in the nugget zones along with the AA6061 matrix. Higher ultimate tensile strength was observed with the single-pass processed surface by 11% than the dual-pass processed surface.