Explanation

The relationship between diffusion coefficient and temperature is D=D0exp [― Q/(RT)], where the energy Q on the index is generally kJ/mol. D0 in the above formula is called the diffusion constant. Generally, lgD is a linear relationship with 1/T through experiments. According to the above formula, an intercept is IgD0. It is easy to calculate the diffusion activation energy for a straight line with a slope of one Q/R. The activation energy of self-diffusion of some metals has a simple relationship with the melting point of metals Q=34Tm. Through the diffusion mechanism, it can be proved that for the self-diffusion of bcc and fcc pure metals, Q=Hf+Hm, where Hf and Hm respectively represent the enthalpy change caused by the formation of vacancy and the movement of vacancy.

Classification