FexCr5Al合金在模拟失水事故下的氧化行为研究

Oxidation Characteristics of FexCr5Al alloys under simulated loss of coolant accident condition

摘要:

本文熔炼制备了4种FexCr5Al (x=13、15、17、18,质量分数,wt%)合金,采用有蒸汽发生器的热重分析仪研究4种合金在1000和1200 ℃蒸汽中氧化2 h的行为。采用XRD、FIB/SEM、EDS和TEM观察分析腐蚀后样品的显微组织、晶体结构和成分。结果表明,4种合金在两种温度下氧化时,氧化动力学曲线均遵循抛物线规律,增加Cr含量合金的抛物线速率常数降低,改善了合金的抗高温蒸汽氧化性能；4种合金的氧化膜均为脊状形貌,主要由α-Al2O3组成。随Cr含量的增加,氧化膜中的孔隙减少,氧化膜与基体的结合性变好,说明增加Cr 含量可以提高氧化膜的致密性和结合力,有助于形成均匀且致密的Al氧化膜,从而提高合金的抗高温蒸汽氧化性能。

Abstract:

In this paper, FexCr5Al (x=13, 15, 17, 18, wt%) alloys were prepared and exposed to 1000 and 1200 ℃ steam for 2 h. The high temperature oxidation behaviors of the alloys were studied by a simultaneous thermal analyzer. The microstructure and composition of the oxide film after oxidation were analyzed using XRD, FIB, EDS, and TEM. It was found that the oxidation kinetics of the alloys at two temperatures followed a parabolic growth law. The parabolic rate constants of the alloys were decreased with an increase in Cr content, and the high temperature steam oxidation resistance of the alloys were improved. The ridged oxide films mainly composed of a-Al2O3 were observed in the four alloys. In comparison with the low Cr alloy, the pores of the oxide film were reduced, and the bonding force of the oxide/matrix interface was improved in the high Cr alloy. Consequently, the compactness and adhesion of the oxide film were improved by increasing the Cr content, which promote the formation of a dense Al oxide film and enhance the high temperature steam oxidation resistance of the alloy.