纳米化纯铁中Al扩散的深度剖析

Depth Profile about Diffusion of Aluminum in Nanocrystalline Iron

纳米铁的晶粒比常规铁的晶粒小得多。铁的晶粒越小,强度和硬度越高,抗摩擦性能也越强。因此,在常规铁板表面生成的纳米铁薄层可以成为铁板的耐磨保护层。但由于纳米铁晶体存在大量的晶界,因此具有很高的活性。按照传统的腐蚀理论,晶界是腐蚀的活性区,导致纳米铁比常规铁更容易被腐蚀。实践证明,经过Al热扩散处理后的纳米铁薄层,可以降低晶界的活性,提高纳米铁薄层的抗腐蚀能力,其性能可相当于价格昂贵的高强度高抗腐蚀的高档钢板。本实验利用SIMS对Al在纳米铁薄层中热扩散行为进行深度剖析。

Size of nanostructured Fe grain is much smaller than that of ordinary ones, which causes higher hardness, higher strength and better wear resisitance. Therefore nanostructured-Fe flim, growing up on the surface of ordinary Fe, can be used as wear resisitant layer. Nevertheless, nano-Fe is very high in its activity for the reason of its numerous boundaries. According to the traditional theories of corrosion, grain boundaries are active zones, which causes that nano-Fe is easier to corrosion than ordinary ones. After treatment with Aluminium diffusion in nano-Fe film, reducing activity of grain boudaries, raising wear resistance of nano-Fe film was proved by practice. The performance is equivalent to premium steel plates of high strength and wear resistance, but with high cost. SIMS （secondary ion mass spectrometry） was used for depth profiling of thermal diffusion of Al in nano-Fe film in this experiment. The depth of Aluminium diffusion in nano-Fe film is much deeper than normal-Fe.