Intermetallic powders of Ni-Al, Cu-Al and Cr-Al systems obtained by the self-disintegration method

The intermetallic compounds of the Ni-Al, Cu-Al and Cr-Al systems are chara cterised by the profitable set of mechanical and physical properties, such as good abrasion resistance, high temperature oxidation and sulfur corrosio n resistance. Alloy powders, among them intermetallic powders, are widely used and method s of their production are under development. The technology described here takes advantage of a natural phenomenon, i.e. self-disintegration which tak es place in alloys containing Al4C3 carbide, e.g. in high aluminium cast ir on. The result of chemical reaction between this carbide and moisture are p roducts of bigger volume. It causes cracking of the matrix, i.e. self-disin tegration into a powder. The physical-chemical principles of the powder pro duction using self-disintegration are presented in this article. In Ni-Al-C, Cu-Al-C and Cr-Al-C alloys, Al4C3 phase is not present in the l iquid melt. Therefore, the presence of a catalysing component, increasing t he chemical activity of carbon, is required. Iron can be one of such additi ons. The mechanism of the influence of the iron on the Al4C3 carbide crysta llisation and the physical-chemical properties of the powders obtained by t he self-disintegration process is presented in this work. Applications (pla sma spraying, powder metallurgy) of the intermetallic powders obtained in t his way are mentioned. (C) 2001 Elsevier Science B.V. All rights reserved.