Effect of Cr on oxidation of Ni-xAl alloy
(1. College of Applied Chemistry, Shenyang Institute of Chemical Technology, Shenyang 110142, China;
2. State Key Laboratory for Corrosion and Protection, Institute of Metal Research,
Chinese Academy of Sciences, Shenyang 110016, China)
2. State Key Laboratory for Corrosion and Protection, Institute of Metal Research,
Chinese Academy of Sciences, Shenyang 110016, China)
Abstract: The oxidation of the Ni-10Cr-xAl(x=7%, 10%, molar fraction) alloys was studied at 1 100 ℃ under 0.1 MPa O2 and compared with that of the binary Ni-7Al and Ni-10Al alloys. The results show that the binary alloys form NiO external scales associated with an internal oxidation of Al. On the contrary, the ternary Ni-10Cr-7Al and Ni-10Cr-10Al form external alumina scale in contact with the alloy substrate. An addition of 10%Cr(molar fraction) into Ni-7Al and Ni-10Al inhibits the internal oxidation of aluminum and considerably reduces the critical content of Al needed to form exclusive alumina scales with respect to binary Ni-Al alloy, providing an example of third-element effect.
Key words: Ni-10Cr-xAl alloy; oxidation; third-element effect