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采用热浸镀法在45钢表面制备出了Fe-Al金属间化合物涂层,并在不同温度下对热浸镀后的试样进行扩散退火处理。通过XRD、SEM等分析手段对扩散退火后的涂层结构和成分进行测试分析,探讨扩散退火温度对涂层的影响及合金层的转变机理。结果表明:扩散温度为700~800℃,合金层主要物相为Fe2Al5和Al2O3;800℃以上时,随着温度的升高,合金层的物相由脆性相(Fe2Al5)向韧性相(FeAl和Fe3Al)转变;1 000℃时合金层完全转变为FeAl和Fe3Al。Fe2A5硬度高但脆性大,易产生裂纹,虽然FeAl和Fe3Al的硬度与Fe2A5的硬度相比有所降低,但其韧性好能有效阻碍裂纹产生及扩展,并与基体结合更加致密。
The Fe-Al intermetallic compound coating was prepared on the surface of 45 steel by hot dipping method, and the samples after hot dipping were diffused and annealed at different temperatures. The structures and compositions of the coatings after the diffusion annealing were analyzed by XRD, SEM and other means to explore the influence of diffusion annealing temperature on the coatings and the transformation mechanism of the alloys. The results show that the main phase of the alloy layer is Fe2Al5 and Al2O3 when the diffusion temperature is 700-800 ℃. When the temperature is above 800 ℃, the phase of the alloy layer changes from brittle phase (Fe2Al5) to ductile phase (FeAl and Fe3Al) transformation; 1 000 ℃ alloy layer completely transformed into FeAl and Fe3Al. Fe2A5 has high hardness but high brittleness and easy to crack. Although the hardness of FeAl and Fe3Al is lower than that of Fe2A5, the toughness of Fe2A5 can effectively hinder the generation and propagation of cracks and make it more compact with the matrix.