Corrosion Behavior of NiAl (1-x) Hfx (x= 0... 0.2) Alloys in Chlorine Based High Temperature Environments
Résumé
Five compositions of (Ni0.5Al0.5)(1-x)Hfx (x=0...0.2) alloys were prepared by centrifugal casting in an inductive furnace. The cast alloys exhibits 3 phases: β-NiAl, NiAlHf (Laves) and Ni2AlHf (Heussler). Their CTEs were found to vary linearly with the hafnium content. Hafnium can be used to adjust the CTE to the substrate CTE. At the same time the prepared alloys are corrosion resistant in chlorine based high temperature environments. For hafnium contents higher than 10 at.%t, it was shown that hafnium addition improves the Cl2 corrosion resistance compared to binary NiAl alloys.