Structure of diffusion layers formed at liquid aluminum alloy-steel contact boundary

The microstructure and composition of diffusion layers that arise upon the spread of the liquid aluminum alloys AL5, AL9, AL852, and A7075 over the St3 steel has been investigated using optical and electron microscopy. The thermophysical conditions of the interaction of the melt with the substrate under which at the boundary of the substrate the plastic transition layer of iron-based solid solution improving quality of the coating is formed have been determined. © 2013 Pleiades Publishing, Ltd

Strength properties and structure of a submicrocrystalline Al–Mg–Mn alloy under shock compression

The results of studying the strength of a submicrocrystalline aluminum A5083 alloy (chemical composition was 4.4Mg–0.6Mn–0.11Si–0.23Fe–0.03Cr–0.02Cu–0.06Ti wt % and Al base) under shockwave compression are presented. The submicrocrystalline structure of the alloy was produced in the process of dynamic channel-angular pressing at a strain rate of 104 s–1. The average size of crystallites in the alloy was 180–460 nm. Hugoniot elastic limit σHEL, dynamic yield stress σy, and the spall strength σSP of the submicrocrystalline alloy were determined based on the free-surface velocity profiles of samples during shock compression. It has been established that upon shock compression, the σHEL and σy of the submicrocrystalline alloy are higher than those of the coarse-grained alloy and σsp does not depend on the grain size. The maximum value of σHEL reached for the submicrocrystalline alloy is 0.66 GPa, which is greater than that in the coarse-crystalline alloy by 78%. The dynamic yield stress is σy = 0.31 GPa, which is higher than that of the coarse-crystalline alloy by 63%. The spall strength is σsp = 1.49 GPa. The evolution of the submicrocrystalline structure of the alloy during shock compression was studied. It has been established that a mixed nonequilibrium grain-subgrain structure with a fragment size of about 400 nm is retained after shock compression, and the dislocation density and the hardness of the alloy are increased

Interconnection of structural characteristics with dynamic properties of A5083 aluminum alloy

In this work, the resistance of high-strain rate deformation and fracture during shock-wave compression of aluminum alloy A5083 previously obtained in two structural states by torsion under high pressure or dynamic pressing is studied. It is shown by electron microscopy that sub-microcrystalline structures differ in the size of grain–subgrains, dislocation density, and ratio of low-angle and high-angle boundaries. It is established that, at the same grain size, the sub-microcrystalline alloy exhibits higher dynamic properties, and after dynamic pressing, it has higher spall strength

Influence of severe plastic deformation on the structure and mechanical properties of eutectic Al-Zn-Mg-Fe-Ni alloy

The structure and phase evolution of the new eutectic high strength aluminium alloy Nikalin were investigated under high pressure torsion (HPT) by several numbers of the revolution of the anvil. The chemical composition of the investigated Nikalin alloy was as follows: Al (base)- 7.22Zn-2.95 Mg-0.52 Fe-0.57 Ni-0.2 Zr. (wt.%). The initial material was a coarse grained cast ingot after homogenization. It was established that the HPT process resulted in the deformation dissolution of the nanosized T-phase precipitates and the formation of a supersaturated aluminum solid solution simultaneously with the strong refinement of the structure to the grain-subgrain size of 130-150 nm. Due to that, the yield stress of the HPT alloy increased by a factor of 1.5, the ultimate tensile strength increased by a factor of 1.4, while preserving good ductility of 6-7%. The observed effect of the additional supersaturated solution upon HPT relative to the homogenized state appeared upon post-deformation annealing at 140 °C. An increase in the microhardness of the HPT alloy due to the MgZn2 phase precipitation was observed at 0.5- hours of annealing. © Published under licence by IOP Publishing Ltd.Russian Foundation for Basic Research, RFBR: 18-03-00102Ministry of Science and Higher Education of the Russian Federation: АААА-А18-118020190116-6The research was carried out within the state assignment of the Ministry of Science and Higher Education of the Russian Federation (theme “Structura”, № АААА-А18-118020190116-6) supported in part by RFBR (project № 18-03-00102). The electron microscopy investigations were performed at the Center of Collaborative Access “Testing Center of Nanotechnologies and Advanced Materials” of the M.N. Mikheev Institute of Metal Physics of Ural Branch of Russian Academy of Sciences

Scaling Analysis of Defect Induced Structure of A6061 Alloy at Dynamic Strain Localization

Plastic strain localization and fracture of dynamically loaded metallic samples, occurred during plug formation, are investigated. These processes are closely related to the instability of plastic flow and can be attributed to structural-scaling transitions in mesodefect ensembles. The multiscale nature of defect structure allows us to use the fractal concept for quantitative analysis of both the fracture surface and the inner structure of a deformed material. The scaling properties of fracture surfaces are established in terms of the roughness index (Hurst exponent) as the characteristics of strain localization and fracture

Effect of Heat Treatment of a Melt on the Structure and Properties of the Corresponding Crystalline Ingots or Castings

Abstract: The modern concepts of the structure of liquid metals and alloys are considered. Several types of microinhomogeneity and microheterogeneity are shown to exist in liquid metal solutions. Their structural state changes as a result of variations in composition, history, temperature, and pressure or the influence of various external actions. Upon subsequent cooling at an appropriate rate, these changes can persist up to liquidus and affect the structure and properties of the solidified alloy. The main attention is paid to the influence of the heating temperature of a liquid metal. For aluminum-based alloys, the possibility of developing the optimum heat-treatment conditions for melting using the results of studying the structure and properties of melts has been shown. This optimized heat treatment of melts is shown to be an effective method to improve the quality of alloys. © 2020, Pleiades Publishing, Ltd

ВЛИЯНИЕ УСЛОВИЙ КРИСТАЛЛИЗАЦИИ НА СТРУКТУРУ И МОДИФИЦИРУЮЩУЮ СПОСОБНОСТЬ Al–Sc-СПЛАВОВ

The study covers the impact of thermo-time processing and cooling rate of molten metal on the crystallization regularities, structure, properties and modifying ability of Al–Sc alloys. The Al–Sc alloys obtained by electrolysis in the KF–NaF–AlF3–Sc2O3 melts at 820–850 °C were used as an initial charge for casting. It was found that changes in overheat values and casting temperatures make it possible to vary the shape, number and size of crystals in a wide range. The modifying effect of the cast and fast-quenched master alloys and alloy produced by electrolysis was tested on Al–4,5%Cu alloys. The greatest refinement of the Al–4,5%Cu–0,4%Sc alloy structure was obtained with the fast-quenched master alloy.Исследовано влияние режимов термовременной обработки и скорости охлаждения металлических расплавов на закономерности кристаллизации Al–Sc-сплавов, их структуру, свойства и модифицирующую способность. В качестве исходной шихты для литья использовали отливки Al–Sc-сплавов, полученные электролизом солевых расплавов KF–NaF– AlF3–Sc2O3 при 820–850 °С. Установлено, что, меняя величину перегрева расплава и температуру литья, можно в широких пределах варьировать форму, количество и размеры кристаллов. Модифицирующее действие литой и быстрозакаленной лигатур, а также лигатурного сплава, полученного электролизом, протестировано на сплавах Al–4,5%Cu. Наибольший эффект измельчения структуры сплава Al–4,5%Cu–0,4%Sc был достигнут при использовании быстрозакаленной лигатуры