INFLUENCE OF STRUCTURAL PARAMETERS ON THE PROPERTIES OF NANOCOMPOSITES

Abstract

The processes of formation of the structure of dispersion-strengthened composite materials, which determines their physical and mechanical properties and therefore is of scientific and practical interest, have been studied. Experimental studies of the mechanism of inclusions crystallization during condensation of a vapors mixture of two metals that do not have solubility in equilibrium conditions have been carried out using the example of the Cu-Mo composite. The structure of the Cu-Mo composite has been studied, as well as the dependence of the size of molybdenum particles on its concentration and temperature of substrate. The influence of the production conditions on properties of dispersion-strengthened composite materials has been studied.

Studies have shown that Cu-Mo composites obtained at t_S = 150 – 450 °C are double-phase: dispersed molybdenum particles are uniformly distributed in the matrix, which is a substitutional solid solution of molybdenum in copper. The particles of the strengthening phase are uniformly distributed throughout the matrix grains. The molybdenum particles are nearly spherical in shape and apparently form during the formation of the Cu-Mo composite at the crystallization front as a result of surface diffusion of molybdenum atoms.

With increasing substrate temperature, the size of the strengthening molybdenum particles and the distance between them increase, resulting in a decrease in microhardness of dispersion-hardened composite. Thus, at a substrate temperature of t_S = 150 °C and a molybdenum content of 0.6% to 5.4%, the average particle size is from 98 Å to 120 Å; at a substrate temperature of t_S = 450 °C and a molybdenum content of 2.0% to 4.0%, the average particle size is from 500 Å to 700 Å; at substrate temperatures of t_S = 150 – 450 °C, the microhardness is H_μ = 850 – 350 MPa, respectively.