Ultrafine-grained, high-strength NiAl with Al₂O₃ and Al₄C₃ nanosized particles dispersed via mechanical alloying in toluene with spark plasma sintering

Abstract

A 50:50 atomic ratio of elemental Ni and Al powders were subjected to Mechanical Alloying (MA) in a toluene medium and were consolidated via Spark Plasma Sintering (SPS). The Transmission Electron Microscopy (TEM) results indicated that the ultra-fine grains (226 ± 107 nm and 307 ± 150 nm) and nanometre-sized Al₂O₃ and Al₄C₃ particles dispersed in the NiAl samples sintered at 900 and 1000° C. A high hardness of 670 HV and a compressive yield strength of 2251 MPa were obtained in the NiAl sintered at 900°C. A maximum plastic strain of ∼16.5% with a compressive yield strength of 2041 MPa was realised for the NiAl sample sintered at 1000°C. The contributions of the grain size and particles to the strength were calculated using the appropriate strengthening models, and the calculated theoretical yield strength of the synthesised NiAl was found to closely match the experimental values.