Internal nitridation of nickel-base alloys. Part 1: Behavior of binary and ternary alloys of the Ni-Cr-Al-Ti system
- Univ.-GH-Siegen (Germany). Inst. fuer Werkstofftechnik
The internal-nitriding behavior of several model alloys of the Ni-Cr-Al-Ti system in an oxygen-free nitrogen atmosphere at 800--1100 C was studied. Thermogravimetry as well as various metallographic techniques (SEM and TEM) were used. It was shown that both the nitrogen solubility and the nitrogen diffusion coefficient are strongly affected by the Cr content of the Ni alloy. Hence, in Ni-Cr-Ti alloys a higher chromium content leads to an increased depth of the internal precipitation of TiN. Nitridation of the alloying element Cr takes place only at high concentrations of Cr. In general, the nitridation rate was found to obey Wagner`s parabolic rate law of internal oxidation. Changes in the parabolic rate constant with alloy composition can be understood by means of thermodynamic calculations in combination with microstructural observations.
- OSTI ID:
- 679202
- Journal Information:
- Oxidation of Metals, Vol. 52, Issue 3-4; Other Information: PBD: Oct 1999
- Country of Publication:
- United States
- Language:
- English
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