Mechanical Alloying Synthesis and Spark Plasma Sintering Consolidation of Al-Ti-Si-W Alloys

Al-Ti-Si-W quaternary powders were mechanically synthesized by planetary ball milling; and further consolidated by spark plasma sintering. The nominal compositions of the quaternary alloys were designed to be Al60Ti30Si5W5 and Al45Ti40Si10W5 (wt.%). The microstructural evolution of intermetallic compounds in Al-Ti-Si-W alloys included titanium aluminide, titanium silicide, and ternary alloys (AlxTiy, TixSiy, and TixAly,Siz), whereas W was embedded in the Al-Ti matrix as a single phase. The phase composition and grain size distribution were investigated using electron backscatter diffraction analysis, in which refined and uniform microstructures (less than 0.3 μm) were attributed to severe plastic deformation and rapid densification of the pre-alloyed powders. The mechanical properties were correlated with the Al content in the quaternary alloys; a high hardness of 1014.6 ±73.5 kg/mm2 was observed.