Cast State Research Articles

Structure and Physical Properties of Cast and Splat-Quenched CoCr0.8Cu0.64FeNi High Entropy Alloy

The article investigates the structure and physical properties of the multicomponent high-entropy alloy CoCr0.8Cu0.64FeNi in the cast and quenched state. The composition of the alloy under study is analyzed using the criteria available in the literature for predicting the phase composition of high-entropy alloys. These parameters are based on calculations of the entropy and enthalpy of mixing and also include the concentration of valence electrons, the thermodynamic parameter Ω, which takes into account the melting point, entropy of mixing, and enthalpy of mixing. Another important parameter is the difference in atomic radii between the alloy components δ. Cast samples of the CoCr0.8Cu0.64FeNi alloy of nominal composition were prepared on a Tamman high-temperature electric furnace in an argon flow using a copper mold. The weight loss during the manufacture of ingots did not exceed 1%, and the average cooling rate was ~ 102K/s. Thereafter, the cast ingot was remelted, and films were obtained from the melt. The splat quenching technique used in this work consisted of the rapid cooling of melt droplets when they collide with the inner surface of a rapidly rotating (~ 8000 rpm) hollow copper cylinder. The cooling rate, estimated from the film thickness, was ~ 106 K / s. X-ray structural analysis was performed on a DRON-2.0 diffractometer with monochromatic Cu Kα radiation. Diffraction patterns were processed using the QualX2 program. The magnetic properties of the samples were measured using a vibrating sample magnetometer at room temperature. The microhardness was measured on a PMT-3 device at a load of 50 g. In accordance with theoretical predictions confirmed by the results of X-ray diffraction studies, the structure of the alloy, both in the cast and in the quenched state, is a simple solid solution of the FCC type. The lattice parameters in the cast and liquid-quenched states are 0.3593 nm and 0.3589 nm, respectively. Measurements of the magnetic properties showed that the CoCr0.8Cu0.64FeNi alloy can be classified as soft magnetic materials. In this case, quenching from a liquid state increases the coercivity. On quenched samples, increased microhardness values were also obtained. This can be explained by internal stresses arising during hardening.

Povećanje otpornosti na trošenje elemenata brodskih dizelskih motora koji se izrađuju od nodularnog lijeva

This paper examines the influence of austempering and shot peening on the wear resistance of ductile iron. Samples for further testing were made from mechanically processed casts. The hardness and microstructure of ductile iron were examined on the prepared samples. Metallographic analysis of ductile cast iron samples in the cast state determined the pearlitic-ferritic structure of the matrix characteristic of this type of cast iron. Pearlite predominates in the structure, and the rest consists of ferrite and graphite nodules. The samples were then austempered. The isothermal conversion was 240 °C. After austempering, the hardness was measured and the microstructure was characterized, and the changes that occurred in relation to the heat-treated ductile iron were studied. Austempering created a new austempered structure, harder than that in the cast state, which led to improved mechanical properties. A needle-like structure of lower bainite (ADI) with high-carbon austenite, untransformed austenite, martensite and graphite nodules was achieved. The selected parameters of the shot peening process deformed the surface of the ADI and achieved a mostly martensitic structure without the presence of a soft phase, which increased resistance to abrasion. Additional hardening of the substrate by the shot peening process resulted in a composite material with the properties of comparative steel parts, which are lighter, cheaper and easier to manufacture, more resistant to wear and quieter in operation. Such material should have an even wider application in mechanical engineering, and thus in the construction of marine machinery and plants.

A Comparative Study on the Hot Deformation Behavior of As-Cast and Twin-Roll Cast Mg-6.8Y-2.5Zn-0.4Zr Alloy.

The Mg-6.8Y-2.5Zn-0.4Zr (WZ73) alloy exhibits different microstructure characteristic after conventional casting compared to the twin-roll cast (TRC) state. Twin-roll casting results in a finer microstructure, where the LPSO phases are more finely distributed and less strongly connected. A transfer of the hot deformation behavior from the as-cast condition to the TRC condition is only possible to a limited extent due to the microstructural differences. Both states show differences in the recrystallization behavior during hot deformation. In the conventional cast state, dynamic recrystallization (DRX) is assumed to be delayed by the occurrence of coarse blocky LPSO phases. Main DRX mechanisms are continuous dynamic recrystallization (CDRX), particle stimulated nucleation (PSN) and twin induced dynamic recrystallization (TDRX). The deformed TRC sample showed pronounced DRX at almost all deformation conditions. Besides the TDRX and the PSN mechanism, kink induced dynamic recrystallization (KDRX) can be observed. Optimum deformation conditions for both states are temperatures from 500 °C to 520 °C, and strain rates ranging from 0.01 s−1 to 0.1 s−1 for the as-cast material as well as a strain rate of 1 s−1 for the TRC material.

Copper Based Alloys Hardenable by Precipitation

The paper presents the experimental research conducted with the purpose of accomplishing long products out of special copper-based alloys, from Cu-Cr-Zr systems, hardenable by precipitation, appropriate for large domains of utilization within top industries realized by modern casting – deforming procedures. Therefore, one of the modern technologic alternatives meeting these requirements is horizontal continuous casting which ensures the realization of long semi-fabricated materials out of special alloys that can be used in cast state and/or plastically deformed, in warmth and/or cold, for the accomplishment of certain products required on the market. The effect of precipitation function of hardening degree applied to the samples put in solution is quantified on consecrated compositions of the Cu-Cr-Zr alloys, containing ˜ 1% Cr and ˜ 0.12% Zr respectively, after the solubility treatment. The macroscopic resistance determinations as well as the electronic microscope and X-ray investigations shall furthermore lead to the accomplishment of a concluding image on the mechanism of precipitation within the analysed systems.Key words: Copper based alloys, horizontal continuous casting.

Вплив магнію на високотемпературну структурно-фазову стабільність сплавів системи Al-Ni-La

The paper considers a relevance of the Al-Ni-La system cast alloys development as promising materials for application at elevated temperatures. The influence of magnesium on the structural-phase characteristics of alloys-representatives with a nickel content of about 2% wt. and lanthanum - about 5,5 and 11,5% wt. were studied in the cast condition and after annealing at 425 ° C for 5 hours. It is shown, that the addition of magnesium in the amount of 0,6 wt%. to alloys with a lanthanum content of 5,5 % wt. helps to increase the size of the lanthanum-containing eutectic component in the cast state, but stimulates its grinding after annealing. Since doubling the lanthanum content, magnesium has almost no effect on the structure of the eutectic in the cast state, but intensifies the process of changing its structure during annealing. In this case, the size of the eutectic components is almost unchanged and can be compared with an undoped alloy. Increasing the magnesium content twice to 1,2% wt. in the alloy with a lanthanum content of 11% wt. leads to a noticeable enlargement of Al11La3 intermetallics. After annealing, this structural component retains the characteristics of a fibrous structure and at the same time increases in size by about half. The magnesium content in the eutectic zones and in the solid solution hardly changes after annealing. The obtained data indicate the possibility of using magnesium as an additional alloying element of cast heat-resistant alloys of the Al-Ni-La system, which is able to simultaneously contribute to their strengthening both under normal conditions and at elevated temperatures. In this case, magnesium, in the amount of about 0,6% wt., also helps to preserve the fine structure of the eutectic components at high temperatures. Keywords: Al-Ni-La, Al-Ni-La-Mg, alloying, structural stability, heat resistance.

Дослідження тривалої жаростійкості титанових матеріалів для гібридних паливних комірок

Hybrid SOFC-MGT systems, which combine a solid oxide fuel cell (SOFC) and a gas microturbine (MGT) are capable of generating clean energy with high efficiency. Compared to large turbines in aviation and other areas of mechanical engineering and energetics, the requirements for mechanical properties of MGT materials in SOFC may be less strong, but one of the most important is resistance to long-term oxidation. For SOFC materials it is considered that oxidation resistance test duration must be not less than 1000 h. In addition, today there is a tendency to developing average-temperature (550—650 oC) SOFC modifications. Physical and mechanical properties, the long-term (1000 hours) oxidation resistance at 600 °C in particular, for a number of titanium alloys and composites depending on their chemical and phase composition and production method have been studied. These materials are promising for gas microturbines of a hybrid system “solid oxide fuel cell — gas turbine”. Cast, thermally deformed (forging, rolling), and heat-treated titanium alloys and also sintered and hot-pressed titanium composites have been investigated. They were compared to the most widely used in mechanical engineering and other industries Ti—6Al—4V alloy. It was shown that materials of the Ti—Al—X system (X = C, Nb, Mo) based on titanium MAX phases with nanolaminate microstructure have an advantage. At the same time, alloys based on titanium aluminides γ-TiAl / α2-Ti3Al in the cast state have the highest long-term heat resistance, as well as the best complex of physical and mechanical characteristics among the studied materials. Keywords: titanium alloys, chemical and phase composition, mechanical properties, long - term heat resistance, fuel cell.

Use of the dactyling effect to obtain a compositional structure in white iron during forming

Cast iron is traditionally used as a casting alloy for the manufacture of products operating in various industries. White cast irons are used for parts with high wear resistance due to the presence in their composite structure a large number of eutectic carbides, which are located around the dendrites of the solid solution and provide a high level of hardness and strength. The location of eutectic colonies in the form of a mesh causes a low level of ability to withstand impact loading, facilitates the chipping of individual “grains” in abrasive wear and limits the use of these alloys. The use of forming process allows us to grind the eutectic mesh in the structure of white cast iron, which significantly improves the complex of mechanical and operational properties. But the low level of plasticity of white cast iron in the cast state does not allow widespread using white cast iron plastic deformation. The possibility of hot deformation of cast iron workpieces with different speeds and schemes was investigated. The deformation rate of alloys was varied due to the use of different equipment for mass and small-series production using different types of metal forming.

Regularities of Formation of Structure, Phase Composition and Properties of Chromium–Manganese Alloys in the Initial Cast State during the Process of Friction Wear

Regularities of Formation of Structure, Phase Composition and Properties of Chromium–Manganese Alloys in the Initial Cast State during the Process of Friction Wear

Підвищення пластичності сплаву системи Al-Si зі зниженим вмістом кремнію шляхом деформаційно-термічної обробки

A method of deformation-heat treatment is considered for Al-Si alloy with 4.5 % silicon, which consists in a series of small hot deformations with intermediate annealing. The proposed method allows one to achieve grinding and spheroidization of silicon inclusions, which in the cast state have the form of lamellar excreta at the grain boundaries and significantly reduce the plasticity of the material. Spheroidization, grinding and mixing of inclusions that are achieved during this deformation-heat treatment lead to significantly increase the ductility of the alloy without loss of hardness. The processes of structure change during the deformation of aluminum alloys with low Si content are insufficiently studied. In particular, of interest was the possibility of increasing the ductility of such materials by grinding and mixing silicon inclusions during hot deformation. In this case, to prevent a decrease in ductility due appearance of microconcentrators of stress in the form of acute angles of the crushed silicon inclusions, the deformation was carried out as a series of stages with intermediate annealing. In addition, it was assumed that the cyclic change of temperature in this mode will contribute to the spheroidization of fragments of crushed silicon inclusions by changing the solubility of silicon in solid solution from temperature. It is shown that the proposed mode of deformation-heat treatment of these alloys of the Al-Si system allows to significantly increase their ductility – the critical degree of deposition (deposition before cracking) from 67.8 % in the cast state to – 92.1 %. The hardness of the material can be increased by hardening under cold plastic deformation. In this case, since the material after deformation-heat treatment is more plastic, it has greater reserves for hardening in this way. It is shown that owing to hard plastic deformation, the hardness of the material of samples with 4.5 % Si, which has undergone deformation-heat treatment, can increase to values of 95 ± 17 HV, which is significantly higher than in the cast state. At the same time, the hardness (and, probably, strength) of a similar cast material can also be increased due to hardening, but to lower values – 67 ± 12 HV. Key words: aluminum, aluminum-based alloy, deformation-heat treatment, silicon inclusions, plasticity, hardness.

Microstructural Characteristics of Oxidation Resistant Cr-Si-Al alloys in Cast State and after High Temperature Heating

Microstructural Characteristics of Oxidation Resistant Cr-Si-Al alloys in Cast State and after High Temperature Heating

Use of polymer concrete for large-scale 3D printing

Purpose This paper aims to focus on the evaluation of a polymer concrete as a three-dimensional (3D) printing material. An associated company has developed plastic concrete made from reused unrecyclable plastic waste. Its intended use is as a construction material. Design/methodology/approach The concrete mix, called PolyBet, composed of polypropylene and glass sand, is printed by the fused deposition modelling process. The process of material and parameter selection is described. The mechanical properties of the filled material were compared to its cast state. Samples were made from castings and two different orientations of 3D-printed parts. Three-point flex tests were carried out, and the area of the break was examined. Computed tomography of the samples was carried out. Findings The influence of the 3D printing process on the material was evaluated. The mechanical performance of the longitudinal samples was close to the cast state. There was a difference in the failure mode between the states, with cast parts exhibiting a tougher behaviour, with fractures propagating in a stair-like manner. The 3D-printed samples exhibited high degrees of porosity. Originality/value The results suggest that the novel material is a good fit for 3D printing, with little to no degradation caused by the process. Layer adhesion was shown to be excellent, with negligible effect on the finished part for the longitudinal orientation. That means, if large-scale testing of buildability is successful, the material is a good fit for additive manufacturing of building components and other large-scale structures.

Properties of welded joints of the Al – Zn – Mg – Ca alloy doped by microadditivies of zirconium and scandium

This work is devoted to the study of the structure and properties of welded joints of hot-rolled sheets from the aluminum alloy Al – 4%Zn – 2.5%Mg – 2.5%Ca – 0.2%Zr – 0.1%Sc. The joints were obtained by manual argon-arc method (TIG-welding) using a wire of own production from the base metal composition (sample AlCa) and standard welding wire Of SvAMg5 alloy (sample AlMg). It is shown that in the cast state the alloy structure consists of an aluminum solid solution (Al) (which contains 2.9% Zn, 2.5% Mg, 0.28% Zr and 0.12% Sc) and eutectic crystals of the phase (Al, Zn)4Ca with a volume fraction of ~7.6%. Microstructural investigation of wrought products showed that the formation of a structure consisting of an aluminum matrix and uniformly distributed spherical particles with a diameter of less than 2 microns occurs as a result of hot rolling with a compression ratio of 95%. The quality of welded joints produced using different additives meets the requirements for the absence of internal defects. The structure in the middle of the joints corresponds to the cast structure of the alloy and has hardness (~80 HV) inferior to the hardness (~105 HV) of the main deformed alloy. Heat-affected zone retains a relatively high hardness (at 95 HV), which is associated with a stabilizing effect of dispersed particles of the eutectic phase (Al, Zn)4Ca, and also presence of nanoparticles of the phase Al3(Zr,Sc) in the original sheet. Additional annealing of welds at 350 oC resulted in degradation of the hardness of the AlMg sample to less than 70 HV and relative cross-sectional hardness equalization in the AlCa sample to more than 90 HV. This effect can be explained by the dispersion hardening in case of the AlCa sample due to the separation of coherent nanoparticles of the Al3(Zr, Sc) phase with the L12 structure during the decay of a supersaturated aluminum solid solution. The results of mechanical tests confirmed the advantages of the strength properties of the AlCa sample over the values of the AlMg sample. All samples in the initial state and annealed sample AlMg have strength coefficients relative to the base metal from 72.4 to 75.3. The greatest mechanical properties can be achieved in the welded joint AlCa in the annealed state: UTS = 274±2 MPa, YS = 181±20 MPa, El = 2.9±0.8 %, which corresponds to a coefficient of more than 80%. This paper was prepared in the framework of the Assignment No. 11.2072.2017/4.6 for implementing a project on the following subject: Developing a process for obtaining deformed semi-finished products made of aluminium-matrix eutectic composites hardened with L12 phase nanoparticles with no quenching applied.

Simulation and verification of thermal conductivity of CuCr30 contact material based on morphological changes of Cr particles

In order to improve the thermal deposition of CuCr contact material for vacuum interrupter, CuCr30 contact material was treated with large deformation treatment to change the morphology and distribution of Cr particles, and the effect of the morphology change of Cr particle on the thermal conductivity of CuCr30 contact material was studied. At the same time, the finite element simulation of the thermal transfer behavior of the extruded and cast CuCr30 contact materials was carried out by using ANSYS software. The studies show that the large deformation treatment (deformation ratio 16:1) changes the morphology and distribution of Cr particles in CuCr30 contact material, making it change from dendritic to longitudinally arranged quasi-fibrous. Influenced by the morphology and distribution of Cr particles, the thermal conductivity of CuCr30 contact material is anisotropic, and the effective thermal conductivity varies significantly with the direction. Indeed along the deformation direction, the thermal conductivity of the extruded state is obviously higher than that of the cast state, increasing by 5.8 %. However, perpendicular to the extrusion direction, the thermal conductivity has little changes, and obvious deposition phenomenon appears in the process of thermal conduction. The finite element simulation results of the effective thermal conductivity of CuCr30 material by ANSYS are in good agreement with the measured results, and the error range is 0.7 %∼1%.

STUDY OF THE STRUCTURE, PHASE COMPOSITION, PHYSICOMECHANICAL PROPERTIES, AND ALSO OPTIMIZATION OF HEAT TREATMENT PROCESSES OF CAST HEAT-RESISTANT NICKEL ALLOY ЕР202 BY THE METHOD OF MATHEMATICAL MODELING

General information about the EP202 heat-resistant weldable alloy with a nickel-chromium matrix is given. Its chemical composition, manufacturing technology, recommended heat treatment modes for short-term and long-term parts, as well as recommended maintenance modes for castings and rodsheets are presented. A description of the structure and phase composition of the alloy in the cast state and after heat treatment is given. The mechanical properties of the alloy depending on the test temperature and heat treatment conditions for longitudinal and transverse specimens are given. The physical properties of the alloy at various temperatures are also described. Further, the study presents the study of the modes of stepwise aging on the structure and mechanical properties of the EP202 alloy. An increase in mechanical properties after two-stage aging in comparison with the initial heat treatment due to a more uniform distribution of the strengthening γ¢-phase over the volume of the alloy was established. With the help of the obtained regression equations, the optimal temperature of the first stage of two-stage aging (540 C) was established, which ensures an increase in the level of impact strength by (20...25) %.

Дослідження мікроструктури і твердості дослідних рейкових сталей в литому стані, після гарячої пластичної деформації і термічної обробки

Дослідження мікроструктури і твердості дослідних рейкових сталей в литому стані, після гарячої пластичної деформації і термічної обробки

Effect of solid-solution treatment on the microstructure and mechanical properties of high-nitrogen FeMnCrNiCo high entropy alloys

The effect of solid-solution treatment on the microstructure and tensile properties of high-nitrogen and nitrogen-free high entropy alloys (FeMnCrNiCo and FeMnCrNiCoN, N=0.36 mass.% and N=0.44 mass.%) has been investigated. It has been established that all materials under study possess an fcc crystal lattice, the lattice parameter of which increases with increasing nitrogen content. In comparison with the cast state, which is characterized by a coarse-grained dendritic microstructure, the alloys after solid-solution treatment show a more homogeneous microstructure. Solid-solution treatment does not significantly affect the mechanical characteristics of the alloys and their fracture micromechanisms.

Влияние добавок углеродных нанотрубок и оксидных нановолокон на механические свойства алюминия АД0 после термомеханической обработки

Cast aluminium composite materials based on AD0 aluminium, reinforced with carbon nanotubes and aluminium oxide nanofibers are obtained. It is shown that the additives of 0.05 wt % of single wall carbon nanotubes (SWCNT) and aluminum oxide nanofibers (AONF) allow increasing ultimate tensile strength of cast metal by 15 % and 16 % respectively. Strengthening of the metal is maintained after cold deformation and annealing. Aluminum AD0 with additives SWCNT or AONF retains high strength after annealing, while aluminum without additives is significantly weakened, this allows to obtain annealed aluminum wire, with a strength limit of 54 – 69 % and yield strength of 53 – 78 % higher than that of metal without additives. The influence of SWCNT and AONF on the size of aluminum grain AD0 in the cast state, after cold deformation and annealing has been studied. Nano-additives have been found to inhibit the growth of metal grains at the stage of collective recrystallization, as well as to influence the process of primary recrystallization of aluminum.

Microstructure and Properties of As-Cast and Heat-Treated 2017A Aluminium Alloy Obtained from Scrap Recycling

The continuous increase in the consumption of aluminium and its alloys has led to an increase in the amount of aluminium scrap. Due to environmental protection, and to reduce the costs of manufacturing aluminum in recent years, a lot of research is devoted to recycling of aluminum alloys. The paper presents the results of research concerning the possibility of manufacturing standardized alloy 2017A from commercial and post-production scrap by continuous casting. Obtained from recycling process ingots were subjected to analysis of chemical composition and intermetallic phase composition. Based on the results of light microscopy (LM), scanning electron microscopy + electron dispersive spectroscopy (SEM + EDS), and X-ray diffraction (XRD) the following phases in the as-cast state were identified: θ-Al2Cu, β-Mg2Si, Al7Cu2Fe, Q-Al4Cu2Mg8Si7, and α-Al15(FeMn)3(SiCu)2. During solution heat treatment most of the primary precipitates of intermetallic phases, like θ-Al2Cu, β-Mg2Si, and Q-Al4Cu2Mg8Si7, were dissolved in the solid solution α-Al, and during natural and artificial aging they precipitate as strengthening phases θ-Al2Cu and Q-Al4Cu2Mg8Si7 with high dispersion. The highest hardness—150.3 HB—of 2017A alloy was obtained after solution heat treatment from 510 °C and aging at 175 °C. In the static tensile test the mechanical (Rm and Rp0.2) and plastic (A5) properties were determined for 2017A alloy in the cast state and after T4 heat treatment. The highest strength properties—tensile strength Rm = 450.5 MPa and yield strength R0.2 = 268.7 MPa with good relative elongation A5 = 14.65%, were obtained after solution heat treatment at 510 °C/6 h/water quenching and natural aging at 25 °C for 70 h. The alloy manufactured from recycled scrap is characterized by relatively high mechanical properties.

Investigating the impact of structure of ferrotita-nium bars obtained by the electroslag remelting method on their crushing capacity

The structure and grinding ability of ferrotitanium ingots of different production methods have been researched. It has been found that the partial decay of primary TiFe2 grains with the formation of TiFe. in the structure of ingots of ferrotitanium ESR at a concentration of Ti 38–4 % improves the ability to crushing. Problem. Electrodes of the basic (fluoride-calcium) type, in particular, the UONI 13/55 brand are used for production of welded products of responsible function. They provide the highest plastic properties of the weld metal at a low content of non-metallic inclusions and gases, which is achieved by deoxidation of metal Mn, Si and Ti, introduced into the coating of the electrodes in the form of ferroalloys. However, in the ferrotitanium FeTi35A of the aluminothermic production method used in the production of welding electrodes, the volumetric part of inclusions reaches 0.3%. In this case, most (up to 70%) are refractory due to aluminum oxides, which contaminate the weld metal. The use of ferrotitanium produced by the electroslag remelting method, with a much lower content of non-metallic inclusions and impurities of non-ferrous metals, allows to improve the quality of the weld metal by reducing the number of exogenous inclusions. However, ingots of ferrotitanium obtained by the method of ESR with a similar content of Ti = 28,5 %–30,0 %, had a fairly low crushing point with the formation of a heterogeneous fraction. Goal. The purpose is to research the structure of ingots of ferrotitanium alloys with different titanium content, and to establish the dependence of the ability to crush on the structure and composition of ingots. Methodology. Ingots of ferrotitanium were obtained by electroslag remelting of combined electrodes composed of strips of low-carbon steel St3 and titanium W1-0 in copper water-cooled crystallizer with a cross section of 80–90 mm. The structure and ability of crushing for ingots with titanium content of 15, 20, 25, 30, 40, 45, 50 and 60 % have been tested. The ingots have been examined in the cast state after cooling in the air. A mixture of hydrofluoric, nitric acid and water in the ratio (1: 1: 3) has been used to researching the microstructure that has been determined using a MIM 8-M metallographic microscope. Crushing ability has been determined by a non-standard method on copra with a vertically falling cylindrical striker. It was found that the ability to crushing was the highest for the production of welding electrodes, ferrotitanium electroslag remelting with a concentration of Ti 38–48 % should be used. Originality. It was discovered that provided a Ti content of 45 % partial decay of primary TiFe2 grains with TiFe formation is observed. Upon cooling, the alloy becomes more balanced. The presence of the TiFe decay phase in the middle of the TiFe2 grain due to the difference in structure creates additional internal stresses and facilitates the destruction of the alloy. Practical value. The grinding coefficient of ferrotitanium ESR with a titanium content of 38–48 % and aluminum-thermal production are almost the same, which facilitates their use in the manufacture of welding electrodes.

Features of the structure and properties of aluminum alloys after processing by dispersed modifiers

Studying the effect of modification with dispersed compositions on the grain structure and mechanical properties of industrial aluminum alloys is the goal of the work. Methodology. Cast aluminum alloys AL4 and AL9 were smelted in an industrial induction furnace. The alloys were modified with dispersed powder of magnesium silicide Mg2Si with a particle size of up to 200 nm. The modifier was introduced in tablet form after melting the charge with mechanical stirring of the melt. The amount of modifier to be added to the melt is calculated (0.1%). Results. The physicochemical properties of dispersed Mg2Si were studied. Experimental melting of AL4 and AL9 casting alloys was carried out. Mechanical properties of alloys were tested and analyzed in the initial state and with processing of Mg2Si melts. Dependences of the particle size and the amount of the modifier on the mechanical properties of the alloys have been established. The mechanism of interaction of the modifier with the aluminum melt during crystallization has been established. In industrial experiments, the most effective size of Mg2Si particles was established to increase σв of alloys from 110 to 260 MPa in the cast state. The optimal content of Mg2Si (0.10%) for increasing σ in aluminum alloys has been determined, and grain refinement in modified alloys and a dispersed structure have been obtained. Scientific novelty. The mechanism of action of the dispersed modifier in the melt, which includes the formation of dispersed crystallization centers, has been established. The optimal amount of modifier for melt processing has been determined and the way to enter it. Practical value. The values of the strength properties of modified alloys on the size of particles and the amount of modifier have been established. Grain refinement and uniformity of the structural components of the modified alloys have been achieved.