The paper presents original experimental data on the viscosity and electrical resistivity of liquid cast irons IChKh28N2 and ICh310Kh24M2F4TR. The authors discuss the measurement results within the framework of the concept of metal melts microheterogeneity. Liquid cast iron in a microheterogeneous state is considered as a dispersed system consisting of dispersed Fe – 30 % Cr particles distributed in a Fe – 3 % C dispersion medium. The concept of colloidal microheterogeneity (microheterogeneity) of Fe – C melts was first formulated by Wertman & Samarin more than 80 years ago and found another confirmation in this work. The introduction of theoretical approaches to the rheology of dispersed systems into the analysis of the temperature dependences of the viscosity of microheterogeneous melts made it possible to estimate the parameters of microheterogeneity: the volume fraction and size of dispersed particles. The volume fraction of dispersed particles was determined using the Taylor equation for the viscosity of dispersed systems and size of dispersed particles – within the framework of the theory of absolute reaction rates. Analysis of the temperature dependences of microheterogeneous melts electrical resistivity within the framework of the theory of transport phenomena (in this case, conductivity) in inhomogeneous media (microheterogeneous melts) made it possible to estimate the volume fraction of dispersed particles. The volume fraction of dispersed particles based on data on the electrical resistivity of liquid cast iron was determined using the Odelevsky equation for the inhomogeneous media conductivity. The cluster size was determined by the ratio of the melt electrical resistivity at the liquidus temperature and the analysis temperature, taking into account the known data for the mean free path and the electron scattering coefficient of liquid iron. The volume fraction of dispersed particles in liquid cast iron was 0.2 – 0.1 at the liquidus temperature. With increasing temperature, the volume fraction of dispersed particles decreases. The cluster size in liquid cast iron was about 3 nm at the liquidus temperature, and with increasing temperature the cluster size decreased to 1 – 2 nm. The results obtained are of practical importance: increasing the performance properties of cast iron castings is possible by high-temperature melt treatment (HTMT) in order to change the crystallization conditions and obtain a modified structure. Studies of the microheterogeneous structure of liquid cast irons and assessment of microheterogeneity parameters make it possible to substantiate and propose the optimal HTMT mode in order to improve the performance characteristics of products made of wear-resistant cast irons alloyed with chromium.
