Oxidation of {gamma}-Ni-Al-Si alloys at 1073 K

Journal Article · Wed Feb 01 04:00:00 EST 1995 · Oxidation of Metals

DOI:https://doi.org/10.1007/BF01046750· OSTI ID:68072

Yi, H C; Smeltzer, W W; Petric, A ^[1]; Shi, S Q ^[2]

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1. McMaster Univ., Hamilton, Ontario (Canada)
2. Whiteshell Labs., Pinawa, Manitoba (Canada)

The formation and development of oxides in Ni-4Al and Ni-4Al-xSi (at.%, x = 1, 3, 5) alloys at 5-9 {times} 10{sup {minus}6} and 1 atm oxygen pressure at 1073 K have been studied. The oxidation rate increased with an increase of silicon content in the alloy at the early stage of oxidation, but decreased after longer time exposure due to formation of an intermediate layer composed of NiO and spinel (NiAl{sub 2}O{sub 4} and Ni{sub 2}SiO{sub 4}) between the top NiO layer and the internal-oxidation zone. This intermediate layer became a barrier for releasing stress, generated by the volume expansion associated with oxidation of solute atoms, resulting in high dislocation density and severe distortion in the internal-oxidation zone for the Ni-Al-Si alloys. In Ni-4Al alloy where no complete intermediate-layer formation occurred, stress was easily released by an enhanced vacancy gradient, and therefore an enhanced vacancy-injection rate into the alloy, resulting in a higher oxidation rate than the situation where a sample was oxidized at an oxygen pressure associated with the dissociation of NiO.

• Sponsoring Organization: USDOE
• OSTI ID: 68072
• Journal Information: Oxidation of Metals, Journal Name: Oxidation of Metals Journal Issue: 1-2 Vol. 43; ISSN OXMEAF; ISSN 0030-770X
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM ALLOYS
NICKEL BASE ALLOYS
OXIDATION
SILICON ALLOYS
STRESS INTENSITY FACTORS
TEMPERATURE RANGE 1000-4000 K