Development of in situ NiAl–Al2O3 nanocomposite by reactive milling and spark plasma sintering

NiAl–10 vol.% Al2O3in situ nanocomposite has been synthesized by reactive milling and subsequent spark plasma sintering. The synthesized nanocomposites have ∼96% of theoretical density after sintering at 1000 °C for 5 min. Microstructural analysis of consolidated samples using TEM has revealed the presence of α-Al2O3 particles of 10–12 nm size in NiAl matrix of submicron grain size. Consolidated NiAl–10 vol.% Al2O3 nanocomposite has shown very high hardness of 772 HV0.3 and compressive strength of 2456 MPa with ∼14% plastic strain. The high hardness and compressive yield strength are attributed to the presence of nanocrystalline α-Al2O3 particles and the appreciable plastic strain is attributed to the submicron grains of NiAl.

Research highlights▶ In situ NiAl – Al2O3 nanocomposites as structural material for high temperature application. ▶ Al2O3 particles formed in NiAl matrix retained their nano size even after consolidation at 1000 °C. ▶ High compressive yield strength are achieved due to the presence of nanocrystalline Al2O3 particles. ▶ Appreciable plastic strain is due to the submicron grains of NiAl.