Metals are characterized by a very low electrical resistance, which increases with temperature and about doubles as a consequence ofmelting. In general, the electrical resistivity of LM increases, when impu­rities enter the melt. However, in the case of a liquid

Figure 11 Dynamic viscosity of liquid Na, Pb-Bi(e), and Pb at normal atmospheric pressure.

300 500 700 900 1100 1300 1500 1700 1900 2100

Temperature (K)

Figure 12 Kinematic viscosity of liquid Na, Pb-Bi(e), and Pb at normal atmospheric pressure.

alloy system that is composed of polyvalent compo­nents’ the resistivity sometimes shows a negative deviation from the additivity of the components’ resis­tivities. The electrical resistivity of LM with rare exceptions (such as Na) increases almost linearly with temperature below the boiling temperature; at high temperatures close to the boiling point, it can increase more rapidly. In many cases, the parabolic function can be used:

r(T;p) = ru + Ar(T — TM) + Br (T — Tm)2 [20]

In 1985, the data on the electric resistivity of liq­uid Na were estimated by Ho and James.82 Later, Bretonnet83 reviewed different sources to obtain cor­relations for the electric resistivity of many pure LM and found that a linear function could be used in most cases. However, for Na, the use of a parabolic function was proposed, which describes its electric resistivity with an uncertainty <4% in the temperature range from normal melting to normal boiling point.34

The electric resistivity of liquid lead at normal atmospheric pressure was measured rather well from the melting point up to about 1300 K. In this temper­ature range, it can be described with a linear function with an uncertainty <2%.34 The precision of data obtained at high temperatures is lower, and they indi­cate a more rapid increase of the Pb electric resistivity with temperature.84 Only a few reliable data sources exist on the electric resistivity of Pb-Bi(e), which are limited to a temperature of 1073 K.25,70,85 The differ­ence between these sources is about 7-8%.

The coefficients of correlation [20] for liquid Na, Pb, and Pb-Bi(e), at normal atmospheric pressure, taken from Sobolev,34 are presented in Table 12;

Figure 13 illustrates the temperature dependence of the calculated electrical resistivities.