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研究了Fe24Mn4Al5Cr合金在800和950℃空气中的循环氧化动力学及氧化层形貌、成分和组织结构。由于Mn元素的选择性氧化,在氧化层与基体之间形成高耐蚀性的贫Mn铁素体层。对贫Mn铁素体层的耐腐蚀性能进行了分析。结果表明,950℃氧化10 h后,氧化层与基体间形成形状弯曲、厚度约6μm、较基体贫Mn(5 at%)、富Fe(85 at%)的铁素体层。降低氧化温度至800℃、延长氧化时间至160 h,氧化层与基体之间形成连续平整、厚度约9μm的贫Mn(6 at%~19 at%)、富Fe(83 at%~72 at%)和富Cr(8 at%)的铁素体层。在1 mol/L Na_2SO_4溶液中于800℃氧化160 h后的铁素体贫Mn层的阳极极化曲线呈自钝化,自腐蚀电位Ecorr由原始合金的–710 m V提高至57 m V,维钝电流密度i_p从3.3μA/cm~2下降至0.7μA/cm~2,耐蚀性能提高。
The cyclic oxidation kinetics and morphologies, composition and microstructure of Fe24Mn4Al5Cr alloy in air at 800 and 950 ℃ were studied. Due to the selective oxidation of the Mn element, a highly corrosion-resistant Mn-depleted ferrite layer is formed between the oxide layer and the substrate. The corrosion resistance of Mn-depleted ferrite layers was analyzed. The results show that, after oxidation at 950 ℃ for 10 h, the shape of the oxide layer between the oxide layer and the substrate is curved with a thickness of about 6 μm, which is lower than that of the matrix with Mn (5 at%) and Fe (85 at%). Mn (6 at% ~ 19 at%), Fe (83 at% ~ 72 at%) with a mean thickness of about 9 μm were formed by reducing the oxidation temperature to 800 ℃ and the oxidation time to 160 h. ) And Cr-rich (8 at%) ferrite layer. The anodic polarization curves of the ferrite-poor Mn layer in a 1 mol / L Na 2 SO 4 solution at 800 ℃ for 160 h were self-passivated. The self-corrosion potential Ecorr increased from -710 mV to 57 mV in the original alloy, Dimensional blunted current density i_p decreased from 3.3μA / cm ~ 2 to 0.7μA / cm ~ 2, the corrosion resistance increased.