Effect of Platinum Addition on Microstructure and Oxidation Behavior of Ni3Al-Base Alloys.

In order to study the effect of Pt on bond coat in thermal barrier coating, the corresponding Pt modified Ni₃Al-base alloys were fabricated using arc melting. The microstructure and the oxidation behavior of the Ni–25Al–xPt (x = 0, 10, 20 and 30 at %) alloys at 1100°C were characterized using X-ray diffraction, scanning and transmission electron microscopy. The experimental results showed that the Ni–25Al–xPt alloys kept a single γ′-Ni₃Al phase structure when Pt content up to 20 at %, while Ni–25Al–30Pt alloy consisted of two-phase structures of γ-Ni and γ′-Ni₃Al, which may be caused by the phase deviation resulting from the volatilization loss of Al. Isothermal oxidation test indicated that the addition of Pt in Ni₃Al-base alloys promoted Al₂O₃ scale formation, affected the oxidation surface morphology, reduced oxidation weight gain and the thickness of the oxide layer. [ABSTRACT FROM AUTHOR]