A study on NiAl produced by pressure-assisted combustion synthesis

Abstract

The production of intermetallic compound was carried out in an electrical resistance furnace in open air under 150 MPa uniaxial pressure at 1050 degrees C for 1 hour using aluminum powder with 15 mu m size and Carbonyl-nickel powder with 4-7 mu m size having 99% and 99.8% purity, respectively. The formation temperature of intermetallic compound was determined by Differential Scanning Calorimeter analysis, and exothermic reaction of powder mixture was determined to occur at 655 degrees C. Optical microscope, scanning electron microscopy and X-ray diffraction analysis were used to characterize produced samples. These samples consist of single phase NiAl with very low porosity. Based on the Archimedes' principle, the relative density of the samples was 99.6%. The microhardness of the samples was approximately 367 +/- 17 HV1.0. it was observed that NiAl intermetallic exhibited good oxidation resistance at high temperatures in open atmosphere. The distribution of alloying elements within intermetallic compound was determined by energy-dispersive X-ray spectroscopy. (C) 2009 Published by Elsevier Ltd.