Investigation of the characteristics of the nanocrystalline Ni3Al-based alloy fabricated by hot pressing and sintering

The characteristics of specimens produced from a Ni3Al-based alloy using four different routes were investigated and different trends during consolidation of mechanically alloyed (MA-ed) powders were characterized and analyzed using microstructural observations; measurement of long-range order (LRO) parameter, micro-strain, and grain size; as well as determination of microhardness and density. In addition, the compressive yield strength and ductility of two series of specimens at different temperatures were determined. It was observed that hot pressing (HP) led to the best consolidation conditions. In addition, high pressure cold pressing (CP)/sintering caused the consolidated specimens to improve. In all specimens, the nature of nanocrystalline powders remained unchanged and the disordered MA-ed powders were ordered during consolidation. The yield strength in both series of specimens anomalously increased with increased temperature by up to 600 C, which later decreased beyond this critical temperature. (C) 2009 Elsevier B.V. All rights reserved.