I. G. Brodova

Evolution of the structure formation during dynamic pressing of the AMts alloy

Results of studies of phase and structural transformations in the aluminum AMts alloy (3003) during deformation by dynamic pressing are presented. Different schemes of loading material and their effect on the structure and properties of the alloy are considered. It has been found out that the formation of a submicrograin structure with a size of fragments of 400–600 nm is observed even after a single pass of the sample through two perpendicularly crossing channels upon increasing speed of the sample from 150 to 300 m/s. It has been found that the hardness of a submicrocrystalline alloy produced by dynamic pressing exceeds the hardness of a hot-pressed rod after subsequent cold-working by a factor of 1.5.

High-speed deformation of metallic materials using channel angular pressing for producing an ultrafine-grained structure

The possibility of producing an ultrafine-grained structure of metals and alloys by dynamic channel angular pressing is discussed using titanium, copper, and aluminum-based alloys as an example. It is established that even one-pass deformation allows one to produce a submicrocrystalline structure with a grain size of 30–350 nm and to enhance the strength properties at a high retained plasticity.

Phase and structural transformations in the Al-Cr-Zr alloy after rapid melt quenching and high-pressure torsion

The influence of the degree of shear strain under a high quasi-hydrostatic pressure on the formation of anomalously supersaturated solid solutions and ultramicrocrystalline (UMC) structure in a ternary Al-Cr-Zr alloy has been studied. The dissolution of aluminides in the three-phase alloy have been investigated. The behavior of the deformed material upon annealing has been studied. It is shown that, because of the decomposition of the supersaturated solid solution, the alloy possesses high thermal stability (to 300°C) and enhanced (by a factor of two) hardness (to 1.2 GPa).

Fracture in stress waves and recompaction during the convergence of austenitic steel 12Kh18N10T shells

Austenitic steel 12Kh18N10T shells subjected to explosive loading are studied by metallographic methods. It is found that two spalls, which stop during convergence before focusing, form in loading according to the first experimental version. In the second version of loading, the flight of the explosion products is confined, and the convergence of a shell is provided up to a deep radius. Nevertheless, spall and shear damages are only partly recompacted. The detected changes in the microstructure and properties of the shells are related to the γ α ′ phase transformation during tension and to dynamic recrystallization and melting during subsequent high-rate deformation.

Structure of diffusion layers that are formed upon spreading of Al-Si melts over the surface of St3 steel

Optical and electron microscopy have been used to study microstructure of diffusion layers that are formed upon spreading of melts of the Al-12%Si and Al-20%Si alloys on steel St3.

Structure of Al-Ti-C master alloys

A binary Al-Ti master alloy of hyperperitectic composition, whose structural characteristics ensure high modifying efficiency, has been prepared by the aluminothermy method. The treatment of the alloy by low-frequency vibrations (LFVs) and its interaction with the carbon emitter of LFVs in the process of crystallization lead to the formation of a ternary Al-Ti-C alloy containing titanium aluminide Al3Ti and titanium carbide TiC. The presence of these phases creates favorable conditions for the formation of solidification nuclei in the aluminum melt when using a ternary master alloy as a modifier. A comparison of the efficiency of the structure refinement when using experimental master alloys and the standard Al-Ti master alloy poured into a metallic chill mold has been performed.

Evolution of the structure and phase composition of rapidly solidified Al-Mg-Mn-Sc-Zr alloys during deformation in a bridgman anvil

Metallography and electron microscopy are used to study the formation of submicrocrystalline and nano-structured states in Al-Mg-Mn alloys with scandium and zirconium during shear at a high hydrostatic pressure. The evolution of the structure and changes in the hardness of the alloys are discussed in relation to their composition and casting and heat treatment conditions.

Structure features of bulk submicrocrystalline aluminum alloys at high-rate deformation

The structure formation in commercial Al alloys subjected to severe deformation by dynamic channel-angular pressing has been experimentally investigated. The dependences of the structural characteristics and hardness on the deformation rate and scheme are analyzed. The optimal deformation modes for the formation of submicrocrystalline materials with high hardness and strength are found.

Effect of time-temperature and low-frequency acoustic treatments of the melt on the structure formation in the Al-5% Fe alloy

Regularities of the structure-formation in the Al-5% Fe alloy under conditions of time-temperature and low-frequency acoustic treatments are studied. A 500-K overheating of the melt above the liquidus temperature was found to cause a sharp change in the conditions of formation of the solid phase at the solidification front and to initiate the formation of a metastable quasi-eutectic structure. An additional low-frequency acoustic treatment increases the effect of the melt undercooling. This leads to the formation of anomalous growth forms of the solid at the lower overheatings of the melt.

Multicomponent Al-Si-based composites

The rapid quenching from melt was used to synthesize high-alloyed hypereutectic silumins with antimony and copper. The silumins were natural composites whose structure consisted mostly of dispersed intermetallic crystals uniformly distributed in the Al matrix. It was found that by selecting the optimum phase composition of the alloy and synthesizing multicomponent compounds, including fusible and refractory components, the linear thermal expansion coefficient can be reduced to 7.8 × 10−6 K−1, or one-third of the corresponding coefficient for unalloyed silumin.