Development of in situ NiAl–Al 2O 3 nanocomposite by reactive milling and spark plasma sintering

Abstract

NiAl–10 vol.% Al 2O 3 in 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-Al 2O 3 particles of 10–12 nm size in NiAl matrix of submicron grain size. Consolidated NiAl–10 vol.% Al 2O 3 nanocomposite has shown very high hardness of 772 HV 0.3 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-Al 2O 3 particles and the appreciable plastic strain is attributed to the submicron grains of NiAl.