The High-Temperature Corrosion Behavior of Feconi-Based High-Entropy Alloys

View Statistics Email Alert RSS Feed

Information

Details

Project title

Code/計畫編號

MOST103-2221-E019-007-MY2

Translated Name/計畫中文名

鐵鈷鎳基高熵合金之高溫腐蝕行為研究

Project Coordinator/計畫主持人

Wu Kai

Funding Organization/主管機關

National Science and Technology Council

Department/Unit

Department of Optoelectronics and Materials Technology

Website

https://www.grb.gov.tw/search/planDetail?id=8362169

Year

2014

Start date/計畫起

01-08-2014

Expected Completion/計畫迄

31-07-2015

Bugetid/研究經費

1253千元

ResearchField/研究領域

材料科技

本研究分三部分探討添加不同元素的三種FeCoNiCr基五元高熵合金，包含FeCoNiCrAl、FeCoNiCrSi及FeCoNiCrMn (以下分別簡稱H5A, H5S及H5M)，在不同條件下的氧化行為。其一是探討FeCoNiCr基五元高熵合金在700~ 950oC空氣下恆溫氧化行為，研究結果顯示，三種合金的氧化動力學皆遵守拋物線律，其中，添加Mn的五元高熵合金的氧化速率常數(kp值)皆遠大於其他合金；而添加Si或Al合金的kp值相對較低。推測生成SiO2及Al2O3是五元含矽及鋁高熵合金的氧化速率遠低於五元含錳高熵合金的主因。第二部分是探討FeCoNiCr基五元高熵合金在700~ 900oC空氣下循環氧化行為，其研究結果顯示，三種合金氧化速率由慢到快依序為H5S合金最慢，H5A合金次之，而H5M合金最快，此結果跟恆溫氧化略微不同，這與氧化後生成的氧化物有關。最後一部分則在探討FeCoNiCr基五元高熵合金，包括FeCoNiCrAl及FeCoNiCrMn在試片表面披覆 2mg/cm2的NaCl後，置於600~ 800oC空氣下的熱腐蝕。研究結果顯示，二種合金的侵蝕深度皆隨著時間增加及溫度上升而增加；整體而言，H5A合金的金屬損失量皆小於H5M合金。由微結構分析得知，二種合金熱腐蝕後的腐蝕生成物不同，其中，H5A生成α-Al2O3及θ-Al2O3；而H5M則生成兩層腐蝕物，包括外層的Mn2O3，內層的(Mn,Cr)3O4及少量的Cr2O3。The main goal of this project is to investigate high temperature oxidation of three quinary FeCoNiCr-based high entropy alloys (HEAs), containing FeCoNiCrAl (H5A), FeCoNiCrSi (H5S), and FeCoNiCrMn (H5M) in various tested conditions. First of all, the oxidation behavior of all the HEAs was studied at 700~ 950oC in dry air. In general, the oxidation kinetics of all the alloys followed the parabolic rate law, and the oxidation rate constants (kp values) of the alloys were strongly dependent on alloy composition. It was found that the Mn-additional alloy revealed the fastest oxidation rates over the temperature range of interest, while the kp values of the Si- and Al-additional alloys were nearly identical and much lower with respect to those of H5M. The formation of Al2O3 and SiO2 was responsible for the lower oxidation rates of Al- and Si-containing alloys, as compared to those of the H5M alloy. Secondly, the cyclic oxidation behavior of all the HEAs was systematically studied at 700~ 900oC in dry air. The results showed that the cyclic-oxidation kinetics of the HEAs followed by the fast to slow rank of H5M > H5A > H5S. A minor amount of FeAl2O4 was observed beneath the spalled alumina scales of H5A which dittened from those in the isothermal oxidation. Finally, The hot-corrosion behavior of H5A and H5M alloys deposited with 2 mg/cm2 NaCl was studied at 600oC~ 800oC in dry air. The results showed that the total depth of attack of the two alloys increased with increasing exposure time and temperature. The metal loss of the H5A alloy was much smaller than that of the H5M alloy. The scales formed on the H5A alloy consisted of α-Al2O3and θ-Al2O3, while, triplex scales formed on the H5M alloy, consisting of an exclusive outer layer of Mn2O3, a heterophasic intermediate layer of (Mn,Cr)3O4 and Cr2O3, and an exclusive inner layer of Cr2O3

Keyword(s)

鐵鈷鎳基高熵合金
高溫腐蝕
恆溫氧化
水汽環境
循環氧化
熱腐蝕
反應機制

DSpace CRIS

The High-Temperature Corrosion Behavior of Feconi-Based High-Entropy Alloys

Details

Description