Mechanism and organization characteristics of hot dip aluminum

The impregnated aluminum is obtained by immersing the pretreated workpiece in a molten aluminum bath for a certain period of time, and infiltrating a layer of aluminum into the surface.

(1) Hot-dip aluminum mechanism The mechanism of hot-dip aluminum is similar to that of hot-dip enthalpy. When liquid aluminum is in contact with iron , the FeAl3 compound is first formed due to the phase interfacial reaction; after that, the diffusion continues, and the FeAl3 layer is thickened. Due to the concentration fluctuation, the Fe2Al5 microdomain appears on the surface of FeAl3: as the AL diffuses further, the Fe2Al5 phase expands continuously. Columnar crystals, the FeAl3 phase gradually decreases.

(2) leaching the aluminum layer substantially organizational characteristics resulting nitrided layer can be divided into two layers: the outermost layer AL-rich, substantially liquid aluminum component: AL sublayer is, of Fe alloy layer, a metal compound mainly Fe2Al5 phase, There is also a small amount of FeAl3, and the Fe2Al5 phase protrudes into the steel in a tongue shape. The Fe2Al5 phase is hard and brittle, and it should be grown as much as possible. It is generally preferred to control it within 1/10 of the layer. Controlling the immersion temperature (700 ~ 730 ° C), adding 2% ~ 6% of Be is beneficial to reduce the thickness of Fe2Al5.

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