Development and Mechanical Properties of In Situ Al<inf>3</inf>Ti-Reinforced Nanostructured AA6061 via Mechanical Alloying

Mechanical alloying (MA) was used to disperse 10 wt.% titanium powder in AA6061 powder. The resultant powder was degassed, and differential scanning calorimetry was performed to determine the temperature for formation of titanium aluminide (Al3Ti). The MA powder was characterized by field emission scanning electron microscopy, x-ray diffraction (XRD) and transmission electron microscopy (TEM). Subsequently, the MA powder was consolidated by spark plasma sintering (SPS) at 500 °C under a pressure of 50 MPa. XRD and x-ray energy-dispersive spectroscopy of spark plasma sintered compact revealed in situ formation of Al3Ti. TEM micrographs of spark plasma sintered sample exhibited Al nanograins (average size 50 nm) in the AA6061 matrix along with the dispersed Al3Ti (average size 200 nm). Hardness, yield strength and compressive strength of the SPSed samples were also evaluated and compared with AA6061.