Infiltration and combustion synthesis of an intermetallic compound Ni3Al

Utilising a combination of infiltration and combustion synthesis, a new method for fabricating a high melting point metallic compound (Ni3Al) with only a few pores and little change in the shape, at a low temperature and at atmospheric pressure, has been established. The main procedure for this method is the dropping of molten aluminium or AlNi alloys (Ni content up to 18 mass%) onto a sintered nickel sample with 34–36 vol.% pores at 1073 K. Immediately after a molten aluminium or an AlNi alloy is dropped onto a sintered nickel sample, the molten metal infiltrates into the sintered material accompanied by an exothermic reaction. When a molten AlNi alloy (with a nickel content of over 10 mass%) is dropped, a Ni3Al material is fabricated with only a few pores and little change in the shape. The addition of nickel to the drop delays the onset of the interfacial reaction though the total heat produced is not very different. The delay in the onset of the interfacial reaction allows the infiltration to finish or proceed to some extent before a certain critical point in the interfacial reaction. As a result, a uniform Ni3Al compound is produced. The experimental data clearly relate to the adiabatic combustion temperatures, which indicates that the heat loss is relatively low. As a result, a high melting point metallic compound can be produced at a low temperature and at atmospheric pressure.