擴散路徑分析模型及其在鎳基合金高溫水氧化研究中的應(yīng)用

擴散路徑分析模型及其在鎳基合金高溫水氧化研究中的應(yīng)用Diffusion Path Analysis Model and Its Application to the Oxidation of Nickel-based Alloys in High Temperature Water

針對Inconel 600和Inconel 690合金在高溫高壓水環(huán)境中生成的腐蝕氧化膜, 提出了擴散路徑分析模型, 闡明了氧化膜微觀結(jié)構(gòu)及其形成機理。基于氧化膜成分、合金成分、以及環(huán)境因素, 構(gòu)建了Inconel 600及Inconel 690合金的Ni-Cr-H2O三元相圖。Inconel 600合金高溫高壓水腐蝕的擴散路徑表明, 其氧化膜由內(nèi)層Cr2O3與外層FeCr2O4尖晶石構(gòu)成。通過Inconel 690合金高溫高壓水腐蝕的擴散路徑分析可知, 氧化膜由單一的Cr2O3構(gòu)成。擴散路徑分析結(jié)果表明, 在Inconel 600氧化膜中, O2-比Cr3+具有更高的擴散速率, 而在Inconel 690氧化膜中, O2-的遷移率較低, 所受阻力較大, 從而使得Inconel 600和Inconel 690合金氧化膜呈現(xiàn)出不同的微觀結(jié)構(gòu)。

A model of diffusion path analysis (DPA) was proposed to describe the microstructure and formation mechanism of oxide films on Inconel 600 and Inconel 690 in high-temperature and high-pressure water. First, a Ni-Cr-H2O ternary phase diagram was plotted according to the known composition of the alloys and oxide films, along with the environment factors. The diffusion path describing the oxidation of Inconel 600 in high-temperature and high-pressure water indicated that the surface films consisted of Cr2O3 inner layer and FeCr2O4 outer layer. According to the DPA for Inconel 690, the surface film was composed of Cr2O3 entirely. The diffusivity of O2- was higher than that of Cr3+ in surface films on Inconel 600. The Cr2O3 film formed on Inconel 690 had a higher resistance to the transportation of oxygen through the film, and thus the mobility of oxygen was low. As a consequence, the surface films formed on Inconel 600 and Inconel 690 exhibited different microstructures.

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