Phase Transformation Behavior of Al2O3 Scale Formed on Pt-Modified γ'-Ni3Al-Based Alloys With and Without Hf Addition
スポンサーリンク
概要
- 論文の詳細を見る
The allotropic phase transformation behavior of Al2O3 scale formed on Ni-22Al-30Pt (in at.%) with and without 0.5Hf was investigated during short-term (i.e., 3 min dwell) cyclic oxidation at 1150℃ in air. Hafnium addition did not appear to affect the oxidation rate in the early oxidation cycles, but it did delay the phase transformation from the metastable θ-Al2O3 structure to the stable α-Al2O3. Small dimples, which corresponded to α-Al2O3 grains, started to form on the Hf-free alloy after only 3 oxidation cycles; whereas, no apparent morphological change of the oxide scale surface was observed on the Hf-modified alloy. The transformation to α-Al2O3 was found to initiate at scale/alloy interface on the Hf-free alloy, but it initiated at gas/scale interface on the Hf-modified alloy. Depth profiling using glow discharge optical emission spectroscopy revealed that Hf enriched at the scale/alloy interface due to Hf rejection associated with the formation of an Al-depleted γ-layer, which has a low Hf solubility. Higher positive strain energy due to Hf solution in the metastable Al2O3 was inferred to be the main contributor to the delayed the transformation.
論文 | ランダム
- 大津市権利擁護調査から見える権利擁護事業の展望 (日本司法福祉学会第5回大会分科会報告)
- 福祉サービス利用援助事業の法的課題 (第46回〔日本社会保障法学会〕大会)
- 社協が進める地域福祉権利擁護事業--実態調査から明らかになったこと (特集 住民とともにある社協活動)
- 支援費制度と障害者福祉の課題
- 福祉サービス利用援助契約と権利保障型後見