Diffusion Processes of Aluminium Coatings for the Protection of Austenitic Stainless Steels

An aluminium-coated austenitic stainless steel has been subjected to heat treatments of various durations. The process has led to the formation of inter diffusion zones with characteristic non-directional and columnar structures. The formation of in termetallic compounds such as NiAl or Ni 3 Al prevails in the non-directional type, while substitutional solid solutions occur in the "columnar " type. One or both these structures can be obtained by balancing and regulating process activity through adequate heat treatments. The development of one or both structures can heighten the characteristics of the coating as regards coating protection or oxidation resistance at high temperatures.