Fe-Al基金属间铝化合物层在酸性条件下的显微组织演变和腐蚀行为（英文）

Microstructure evolution and corrosion behavior of Fe-Al-based intermetallic aluminide coatings under acidic condition

采用压力辅助固态扩散结合技术在430 (Fe-Cr)和304 (Fe-Cr-Ni)不锈钢基体上制备两种Fe-Al基金属间铝化合物层,并与在纯铁上制备的铝化合物层进行比较。采用SEM、EDS和EBSD分析铝化合物层的显微组织和存在的金属间化合物物相。Al和基体发生相互扩散,生成在Fe_4Al_(13)基体上弥散分布的Cr_2Al_(13)网状结构。采用失重实验、OCP、Tafel曲线和EIS实验研究金属间化合物层在0.5mol/L盐酸溶液中的腐蚀行为。结果表明,与纯铁上的铝化合物层相比,同时添加Cr和Ni后,304不锈钢上铝化合物层的耐蚀性提高了十几倍,而430不锈钢铝化合物层中裂缝的存在使得腐蚀介质渗透至基体,提高了腐蚀速率。此外,采用XRD分析腐蚀产物。结果表明,Cr和Ni的添加能促进耐蚀相的形成,从而提高不锈钢上金属间铝化合物层的耐蚀性。

Two Fe-Al-based intermetallic aluminide coatings were fabricated on 430-SS(Fe-Cr)and 304-SS(Fe-Cr-Ni)substrates by pressure-assisted solid diffusion bonding with coating on pure Fe as control.The microstructure and intermetallic phases of the coatings were characterized by SEM,EDS and EBSD.A network of Cr2Al13 with matrix of Fe4Al13 was formed by inter-diffusing of Al with the substrates.The corrosion behavior of intermetallic coatings was investigated in 0.5 mol/L HCl solution by mass-loss,OCP,Tafel plot and EIS.It was found that corrosion resistance was greatly enhanced by dozens of times after the addition of Cr and Ni compared with that on pure Fe.The presence of cracks in the coating on 430-SS provided a pathway for corrosion media to penetrate to the substrate and accelerated the corrosion rate.Moreover,the corrosion product was analyzed by XRD,demonstrating that the addition of Cr and Ni facilitated the formation of more corrosion resistant phases,and therefore improved corrosion resistance.