I. E. Ignat’ev

Production of nickel and iron nanopowders by hydrogen reduction from salts

The formation of nickel and iron nanoparticles produced by a chemical—metallurgical method and steels made of composite iron powders with nanosized nickel additions is studied. A procedure is developed for calculating the nanopowder particle size and the activation energy of sintering. The results obtained make it possible to decrease the temperature of the process of powder production, to decrease the energy consumed for powder sintering, and to predict the powder nanoparticle size.

Pseudocavitation during low-frequency treatment of melts

Low-frequency and ultrasonic treatments of a melt are compared theoretically. The phenomenon caused by low-frequency treatment of a melt and called pseudocavitation is considered. The conditions of the appearance of this phenomenon are revealed, and an experiment on mixing of a “light” aluminum powder with “heavy” Wood’s alloy is performed under pseudocavitation conditions.

Principal distinction of the methods of low-frequency and ultrasonic effects on melts

Factors that determine the difference between low-frequency and ultrasonic treatments methods are discussed: cavitation phenomena, dissipative losses, and the possibility for the turbulent mixing of the melts. The independence of each method is proven.

Mathematical Model of the Melt Impregnation of Metal Powder Using Vibration Treatment

A model of the melt impregnation of metal powder under low-frequency vibration is presented in the form of mathematical dependences. The influence of factors such as the powder dispersity, its wetting with the melt, melt viscosity, and conditions and parameters of the vibration treatment are considered. The results of simulation are confirmed by the experimental data found using vibration treatment and without it. Recommendations on the selection of amplitude-frequency parameters are elaborated.

Combined Low-Frequency and Electro-Impulse Treatment of Molten Metal

A method is given for preparing alloy using combined low-frequency and electro-impulse action on a melt. Metallographic comparison is provided for the result of using this procedure with results of preparing alloy with separate low-frequency and electro-impulse methods on the example of alloy of the Al–Ti–C system. It is established that melt treatment by the new method leads to a variety of aluminide growth shapes.

On the “elasticity” of waves during vibrating action on a melt

The problem of the elasticity of the ultrasonic and low-frequency waves generated in a metallurgical melt by a vibrating piston is theoretically considered on the basis of acoustic equations and experimental data. The modes of vibration treatment of melts where a wave can or cannot be considered as elastic have been determined.

Preparation of Alloys of the Al–Nb System Using Melt Low-Frequency Treatment

It is shown that use of low-frequency action on a melt increases significantly the quality and efficiency of preparing alloy of the Al–Nb system compared with normal temperature and time treatment; it increases niobium aluminide content within the alloy, and reduces melt treatment duration to 5–10 min. The effect of prolonged vibration action on intermetallic size is explained.

Steel-aluminum layered composite with a nanostructured intermediate layer

The results of an investigation into the influence of the degree of deformation on the structure of components of the layered steel-aluminum composite are presented. It is shown that the noticeable structural variations start from reduction ratio ɛ > 75%, or e > 1.54 in logarithmic units. The plastic deformation mechanism of a brittle intermetallic layer is described. It is shown that the viscoplastic intermediate layer of the steel-aluminum layered composite can be obtained by rolling when bringing the deformation ratio to 90%. As for the submicron structure, it can be obtained at ɛ > 95%, or e > 3.

Features of the low-frequency treatment of melts

A method for obtaining cast composites using the effect of low frequencies on the melt is presented. Some features of the process and the results of vibrational treatment are unobvious and require theoretical explanation. The factors that prevent the introduction of the powders into the melt volume and the factors affecting the variation in the sizes of the structural components of the melt during low-frequency melting are considered. A new interpretation of the crushing and coagulation mechanism during low-frequency treatment (LFT) with a mathematical description and experimental confirmation is proposed.

Analysis of the refinement and coalescence of solid particles during low-frequency treatment of metal melts

The refinement and subsequent coalescence of powder particles and the related aluminides forming during low-frequency treatment of aluminum composite melts are studied. The milling of the initial particles to the limiting size of several micrometers and their subsequent association into conglomerates and a mathematical description of these processes are presented in terms of a new approach.