Microstructure and mechanical properties of nanocrystalline Al–Ti alloys consolidated by plasma activated sintering

Abstract Nanocrystalline Al–Ti alloys were produced by reactive ball milling and subsequently plasma activated sintered (PAS). The consolidation behavior and microstructure of the nanocrystalline alloys were studied as a function of sintering pressure and temperature with constant holding time of 60 s. This showed that the pressure and temperature had large effects on the final density and grain size. The PAS consolidated Al–Ti alloys exhibited full density (99% of theoretical density) while retaining a grain size of the order of 50–100 nm at a temperature of 500°C with a pressure of 75 MPa. This alloy showed a much more uniform grain distribution and finer grain size compared with Al–Ti alloys manufactured by conventional consolidation methods. At room temperature, the compressive yield strength (about 692 MPa) of PAS alloy was much higher than that of hot pressed Al–Ti alloys. The higher yield strength is considered to be due to the effect of grain refinement strengthening. At all temperatures above 300°C, the PAS alloys exhibited plastic strain beyond 60%.