Reactive pressing of intermetallics

This paper discusses the reactive pressing (RP) of Ni3Al from nickel (Ni) and aluminum (Al) elemental powder compacts. The effect of varying pressure and temperature on the microstructure and properties was examined. Three pressures (100, 200 and 300 MPa) were applied at three different temperatures (1000, 1100 and 1200 degrees C) while the pellet cooled down from the maximum combustion temperature. The results show that as both of the pressure and temperature increase, the product porosity decreases with a corresponding increase in microhardness (HV). The grain size was almost independent of both pressing temperature and pressure. The results were statistically analyzed to arrive at response surfaces that predict residual porosity, grain size and microhardness at any given pressure/temperature combination. X-ray diffraction (XRD), scanning electron microscopy, image analysis and Archimedes principle were used to study the effect of processing parameters on the final residual percentage total porosity, microstructure, average grain size (d(av)), and microhardness of RP-Ni3Al alloys. (c) 2006 Elsevier B.V. All rights reserved.