【摘 要】
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The RE-aluminized coating and pure aluminized coating on 20 carbons steel were prepared by hot dip aluminizing method at 740 ℃. After diffusion treatment at 85
【机 构】
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Department of Materials Engineering,Department of Mathematics and Information Sciences
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The RE-aluminized coating and pure aluminized coating on 20 carbons steel were prepared by hot dip aluminizing method at 740 ℃. After diffusion treatment at 850 ℃ for 4 h, the distribution of aluminum and lanthanum elements in the coating was analyzed with energy disperse spectroscopy(EDS) and electron probe microanalyses(EPMA), and the lattice parameter of α-Fe in the matrix of the coating was measured precisely by X-ray diffractometer(XRD). The results show that RE permeates into the aluminized coating, leads to lattice disturbance and increases the depth of the aluminized coating. On the basis of the results, the expression of the diffusion coefficient of Al atoms is derived from the diffusion flow, and the effect of the high vacancy concentration and high concentration gradient of vacancies on the diffusion of Al atoms was analyzed by establishing the kinetics model of the vacancy mechanism of diffusion. The results show that the high vacancy concentration and high concentration gradient of vacancies in the RE-aluminized processes are the main reason why the diffusion coefficient of Al atoms in RE-aluminizing is bigger than that in pure aluminizing.
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