A. I. Bazlov

Structure and mechanical properties of Ni-Cu-Ti-Zr composite materials with amorphous phase

The structure of specimens of Ni-Cu-Ti-Zr alloys with an amorphous phase has been examined by X-ray diffraction, as well as by transmission and scanning electron microscopy. Mechanical characteristics of the alloys have been determined using universal testing machines. Transformation-induced plasticity has been found to exist. The specimens demonstrate a good combination of strength and plasticity owing to both the composite effect of a heterophase structure and the dynamic martensitic transformation that develops during deformation.

Development of mathematical models of superplasticity properties as a function of parameters of aluminum alloys of Al-Mg-Si system

The article discusses the superplasticity properties and structure parameters of cold-worked alloys of a quasi-binary section of the Al-Mg-Si system with a volume fraction of eutectic particles of 0.08–0.18. Mathematical models of yield stress and effective elongation as a function of the structure and engineering parameters have been developed for alloys of this system. An analysis of the developed models shows that, in the temperature range of 520–560°C, superplastic deformation is controlled by the rate of diffusion of aluminum atoms in the grain bulk.

Studies of the structure and mechanical properties of Ti43.2Zr7.8Cu40.8Ni7.2Co1 alloy containing amorphous and crystalline phases

The structure and mechanical properties of Ti43.2Zr7.8Cu40.8Ni7.2Co1 alloy cast into a massive copper mold are studied. It has been shown that, after the fast cooling of the alloy, the structure consists of amorphous matrix and crystal particles distributed in the matrix; hence, the alloy displays high strength (higher than 1600 MPa) and relatively high plasticity (1%). Modeling the strain of the alloy using the finite elements method has shown that the crystal particles in the amorphous matrix are effective barriers for the propagation of shear bands, thus stimulating nucleation and the development of new shear bands and increasing the plasticity of the material in general.

Comparative analysis of the structure of palladium-based bulk metallic glasses prepared by treatment of melts with flux

A comparative analysis has been presented of structural features of palladium-based bulk metallic glasses prepared by argon gas casting into a copper mold after treatment of melts with a flux and studied using X-ray synchrotron radiation. The radial distribution functions have been calculated. The short-range order (in the first and second coordination shells) and the medium-range order (from the third to several subsequent coordination shells) in atomic arrangement have been analyzed.

Effect of Multiple Alloying Elements on the Glass-Forming Ability, Thermal Stability, and Crystallization Behavior of Zr-Based Alloys

Effect of multiple alloying elements on the glass-forming ability, thermal stability, and crystallization behavior of Zr-based glass-forming alloys were studied in the present work. We investigated the effect of complete or partial substitution of Ti and Ni with similar early and late transition metals, respectively, on the glass-forming ability and crystallization behavior of the Zr50Ti10Cu20Ni10Al10 alloy. Poor correlation was observed between different parameters indicating the glass-forming ability and the critical size of the obtained glassy samples. Importance of the width of the crystallization interval is emphasized. The kinetics of primary crystallization, i.e., the rate of nucleation and rate of growth of the nuclei of primary crystals is very different from that of the eutectic alloys. Thus, it is difficult to estimate the glass-forming ability only on the basis of the empirical parameters not taking into account the crystallization behavior and the crystallization interval.

Influence of Al3Ni crystallisation origin particles on hot deformation behaviour of aluminium based alloys

Abstract Binary Al–Ni, Al–Mg and ternary Al–Mg–Ni alloys containing various dispersions and volume fraction of second-phase particles of crystallisation origin were compressed in a temperature range of 200–500 °C and at strain rates of 0.1, 1, 10, 30 s−1 using the Gleeble 3800 thermomechanical simulator. Verification of axisymmetric compression tests was made by finite-element modelling. Constitutive models of hot deformation were constructed and effective activation energy of hot deformation was determined. It was found that the flow stress is lowered by decreasing the Al3Ni particle size in case of a low 0.03 volume fraction of particles in binary Al–Ni alloys. Intensive softening at large strains was achieved in the alloy with a 0.1 volume fraction of fine Al3Ni particles. Microstructure investigations confirmed that softening is a result of the dynamic restoration processes which were accelerated by fine particles. In contrast, the size of the particles had no influence on the flow stress of ternary Al–Mg–Ni alloy due to significant work hardening of the aluminium solid solution. Atoms of Mg in the aluminium solid solution significantly affect the deformation process and lead to the growth of the effective activation energy from 130–150 kJ/mol in the binary Al–Ni alloys to 170–190 kJ/mol in the ternary Al–Mg–Ni alloy.

Investigation and simulation of crystallization of bulk zirconium-based metallic glasses

This article is devoted to the investigation and simulation of the crystallization kinetics of zirconium-based bulk metallic glasses under heating with a constant rate, as well as under isothermal holding at an elevated temperature. The investigation into crystallization kinetics with time can provide a deeper under-standing of the crystallization mechanism of bulk metallic glasses and promote the scientifically substantiated selection of thermal treatment modes to form the desired structure and properties of composite materials on their basis.

On Temperature Rise Within the Shear Bands in Bulk Metallic Glasses

Room temperature deformation process in a bulk metallic glassy sample was studied by using a hydraulic thermomechanical simulator. The temperature rise during each separate shear band propagation event was measured with a high data acquisition frequency by a thermocouple welded to the sample. Calculation showed that when propagation of the well developed shear bands takes place along the entire sample the temperature inside the shear band should be close to the glass-transition temperature. It was also possible to resolve the temporal stress distribution and a double-stage character of stress drops was also observed. The obtained results are compared with the literature data obtained by infrared camera measurements and the results of finite elements modeling.

Investigation of the Structure and Properties of the Fe-Ni-Co-Cu-V Multiprincipal Element Alloys

The effect of V addition to the Fe-Ni-Co-Cu system was analyzed in the present work. Three distinct alloys were prepared in a vacuum electric arc furnace in an argon atmosphere and later cast into a copper mold. Investigation of the structure of alloys was performed by scanning electron microscopy (SEM) and by X-ray diffraction. The mechanical properties were also tested in compression. The phase diagrams of the Fe-Ni-Co-Cu-V system were thermodynamically calculated and the results are compared with those of differential scanning calorimetry and the results of SEM observation. It is shown that as a result of crystallization, two solid solutions with FCC crystal structures are formed. The addition of equiatomic amount of vanadium to Fe-Ni-Co-Cu system alloys facilitates phase separation in the liquid state. The addition of V causes an increase in the yield strength by solid solution hardening by about 30 pct and maximum true stress by 40 pct, yet retaining good plasticity. It also does not cause formation of an intermetallic compound.