LASER-SURFACE-ALLOYING OF THE IRON-BASED SUPERALLOY INCOLOY-800H WITHAL

Laser surface alloying by the powder feed method of the iron based sup eralloy Incoloy 800H with aluminium has been carried out. The effects of different preparation parameters, like laser scan speed and powder feed rate, on the morphology of the alloyed zone have been investigate d. Microstructure and composition have been determined by scanning ele ctron microscopy (SEM), optical microscopy, and xray fluorescence spec troscopy. Three different phases with different Al-content have been d istinguished. The observed Al-enrichment at the surface, the presence of NI-AI and Fe-Al intermetallic compounds, and the considerable grain refining of the alloyed zone with respect to the substrate, make this surface modification technique a very good method to improve the corr osion behaviour of the Incoloy 800H superalloy.