Increasing Aluminum Content Research Articles

CREATION OF ELECTRIC CONDUCTIVE COATINGS USING GAS-DYNAMIC SPRAYING

The article presents the results of research on the processes of creating conductive coatings based on copper and aluminum in order to determine the interaction of components on each other during cold gas-dynamic spraying (CGDS) and substantiate the method of introducing an additional component to obtain the desired composite coating. In particular, under conditions when the copper sputtering coefficient is almost zero (at a working air temperature of 300 °C), it is the search for the experimental dependence of the sputtering coefficient on the percentage of copper and aluminum powders in the sprayed mixture, determining their residual content in the coating and then calculating based on these data, the sputtering coefficients of copper and aluminum. The CGDS method obtained samples with composite coatings from mixtures of aluminum and copper powders at different initial mass concentrations of aluminum (from 0 to 100%, in increments of 10%) Other things being equal (air pressure 0,6 MPa, air heating temperature 300 ° C) . The spraying ratio of the mixture and the residual content of the components in the obtained composite coatings were measured. Data on the residual content of the components in the coating allows you to select the composition of the source powder required to obtain a given content of components in the coating. The dependences of the sputtering coefficients of copper and aluminum on the mass content of aluminum in the sprayed mixture are found. At an initial concentration of aluminum less than 66%. the coefficient of copper sputtering is higher than the coefficient of sputtering of aluminum. Both increase monotonically with increasing aluminum concentration until it reaches 61%. At high concentrations of aluminum (more than 66%) the spray coefficients of copper, aluminum and their mixtures coincide. The obtained data on the residual content of the components in the coating allows you to select the composition of the source powder required to obtain a given content of components in the coating. For example, the maximum residual copper content (~ 95%) can be obtained by adding to the source powder 30-40% aluminum. The obtained results confirm the interaction of the components on each other and justify the method of introducing an additional component to obtain a composite coating containing a component that is difficult to spray.

The influence of aluminum on the formation of the hardening phase in magnesium alloys

Purpose. Study of the effect of alloying with aluminum on structure formation, mechanical properties and heat resistance of magnesium alloys
 Research methods. Methods of metallographic and micro X-ray spectral analysis. Determination of mechanical properties and heat resistance.
 Results. The regularities of the influence of alloying with aluminum on the formation of the hardening phase in magnesium alloys have been investigated. It is shown that an increase in the concentration of aluminum in magnesium alloy promotes refinement of the macro- and microstructure of the metal (reduces the grain size and the distance between the second-order dendritic axes) and also increases the amount of intermetallic phase. The positive effect of aluminum additives on the mechanical properties and heat resistance of cast metal has been established.
 The optimal level of alloying with aluminum (about 7,7 %) hes been determined, which ensures a sufficient level of mechanical properties and heat resistence.
 Scientific novelty. Based on the regression analysis of the experimental data, empirical equations were obtained that describe the dependences of the size of macro- and micrograins on the concentration of aluminum in magnesium alloys. It is shown that the optimal aluminum content in the magnesium alloy in the amount of ~ 7,7 % provides the best combination of mechanical properties (a sufficiently high strength and the highest plasticity) and heat resistance
 Practical value. It has been established that alloying magnesium alloys with aluminum is promising for improving the structure and increasing the mechanical properties and heat resistance of cast metal. This effect makes it possible to significantly expand the field of application of magnesium alloys in mechanical engineering and improve the performance of various equipment.

The Influence of Varying Aluminium and Manganese Content on the Corrosion Resistance and Mechanical Properties of High Strength Steels

The aim of this paper is to evaluate the influence of small variations in chemical composition on the corrosion resistance and mechanical properties of low-manganese and medium manganese high strength steels. Six different steels with manganese content varying from 1.5 to 4.0 wt.% and aluminium from 0.008 to 6.5 wt.% were subjected to the analysis. The other subjects for evaluation included the effect of aluminium as a replacement for silicon, niobium microalloying and the effect of heat treatment. The effect of non-metallic inclusions on localized corrosion initiation and propagation was also documented. Using potentiodynamic testing, exposure testing, tensile and impact testing, it was found that the improvement in corrosion resistance associated with increasing aluminium content is accompanied by a significant deterioration of the mechanical properties. Niobium microalloying and heat treatment was found to have no quantifiable impact on the anti-corrosion properties. The effect of aluminium content proved to be superior to the effect of nonmetallic inclusions in terms of determining the overall corrosion resistance of the experimental steels.

Corrosion Properties of Mn-Based Alloys Obtained by Aluminothermic Reduction of Deep-Sea Nodules.

Deep-sea manganese nodules are polymetallic oxidic ores that can be found on a seabed. Aluminothermic reduction is one of the possibilities of manganese nodules processing. This process obtains the polymetallic alloy with a high content of Mn and a varying content of Al, depending on the ratio between aluminum and nodules. The corrosion behaviors of three experimental Mn-based alloys produced by aluminothermic reduction with a content of Mn > 50 wt % were studied. The electrochemical testing in potable water and model seawater was used to explain the corrosion mechanism of Mn-based alloys. The results showed that the corrosion rate of experimental Mn-based alloy decreases with the increase in aluminum content in both potable water and model seawater. It was observed that the uniform corrosion of experimental Mn-based alloys is changed with an increase in aluminum content in alloy to localized corrosion, which was caused by microcells in an environment of model seawater. In contrast, the formation of a semi-protective layer of corrosion products was observed on the surface of Mn-based alloys with a higher content of aluminum in potable water. Moreover, the pitting corrosion of tested Mn-based alloys was observed neither in potable water nor in model seawater.

Lanthanum Strontium Cobaltite-Alumina Fiber Composite Contact Material for Solid Oxide Fuel Cells

Short alumina fibers were added to LSCo contact material to enhance the contact strength and improve thermal cycle stability. Alumina fiber from 2.5 v% to 20 v% were mixed with LSCo and sintered at elevated temperatures. Sintering study showed retardation in densification of LSCo matrix with increasing alumina content. Sintered bulk strength exhibited similar behavior where strength greatly reduced at high alumina v%. Coefficient of thermal expansion showed consistent results with prediction from rule of mixture. Contact strength using anode supported YSZ bilayer coupons improved greatly with the presence of small amount (2.5-5 v%) alumina fibers and no substantial reduction after 10 deep thermal cycles. Candidate LSCo-Al2O3 contact materials was validated in a generic stack test fixture for 1000h at 800oC followed by 10 thermal cycles. Results of impedance analysis showed substantial improvement in thermal cycle stability as compared to LSCo parent materials.

Electron Beam Powder Bed Fusion of γ-Titanium Aluminide: Effect of Processing Parameters on Part Density, Surface Characteristics, and Aluminum Content

Gamma titanium aluminides are very interesting for their use in high-performance applications such as aircraft engines due to their low density, high stiffness and favorable high-temperature properties. However, the pronounced brittleness of these intermetallic alloys is a major challenge for their processing through conventional fabrication methods. Additive manufacturing by means of electron beam powder bed fusion (EB-PBF) significantly improves the processability of titanium aluminides due to the high preheating temperatures and facilitates complex components. The objective of this study was to determine a suitable processing window for EB-PBF of the TNM-B1 alloy (Ti-43.5Al-4Nb-1Mo-0.1B), using an increased aluminum content in the powder raw material to compensate for evaporation losses during the process. Design of experiments was used to evaluate the effect of beam current, scan speed, focus offset, line offset and layer thickness on porosity. Top surface roughness was assessed through laser scanning confocal microscopy. Scanning electron microscopy, electron backscatter diffraction (EBSD) and energy-dispersive X-ray spectroscopy (EDX) were used for microstructural investigation and to analyze aluminum loss depending on the volumetric energy density used in EB-PBF. An optimized process parameter set for achieving part densities of 99.9% and smooth top surfaces was derived. The results regarding microstructures and aluminum evaporation suggest a solidification via the β-phase.

Microstructural characterization and corrosion behavior of AlxCoCrFeNi high entropy alloys

In this study, AlxCoCrFeNi high entropy alloys (x = 0, 0.25, 0.75, 1.25 and 2) with multiprincipal elements were prepared by induction-melting in Ar atmosphere. The microstructural evaluation showed that with increasing aluminum content, the AlxCoCrFeNi alloys change from a single FCC phase to a single BCC phase with a transition duplex FCC/BCC region. Moreover, the increase of aluminum led to dendritic structure in associated with elemental segregation and alloy strengthening. The highest hardness (700 HV) was observed to be achieved for x = 0.75, in which the structure changed from FCC to FCC/BCC dual phase. The potentiodynamic polarization test of the AlxCoCrFeNi alloys showed that the corrosion current densities increased with increment of molar ratio of aluminum element. The FCC structure is a corrosion resistant phase regarding to promotion of polarization resistance values. Also, EIS test demonstrated that with increasing molar ratio of Al and presence of BCC phase, the value of corrosion resistance reduced due to passive layer properties and elemental segregation.

Microstructure and indentation hardness study of CAE-PVD (Cr,Ti,Al)N solid solution coatings deposited using a combinatorial multitarget approach

In this study we have analysed the indentation hardness and modulus of cathodic arc deposited CrTiAlN coatings as a function of the stoichiometric variables Ti/Cr, Al content and cation mix. The coatings have been prepared using a combinatorial cathode composition approach, leading up to 14 different stoichiometries produced in 5 batches. The coatings have been inspected by glow discharge optical emission spectroscopy, scanning electron microscopy, X-ray diffraction and nanoindentation techniques. The coatings develop crystalline structures compatible with solid solutions of face–centered cubic unit cells for all the compositions produced. Such unit cells exhibited a downwards lattice parameter dependency on the aluminum concentration of the coatings (from 0.417 nm down to 0.413 nm). The indentation hardness as a function of the Ti/Cr is compatible with other previous studies reported. The films hardnesses and moduli also increase as the aluminum concentration increases (21 GPa up to 34 GPa). Both indentation responses upon Ti/Cr and Al are attributed to solid solution strengthening. However in order to prove this statement, the indentation hardness and modulus were studied as a function of the mixing term of the cations, as this term is well representative of the solid solution compositional map. The observed results unambiguously evidence that the solid solution strengthening effect is confirmed on the basis of the dependency between the indentation hardness and the so called degree of mixing. • CrTiAlN arc coatings deposited using a multi-cathode combinational approach. • CrTiAlN coatings form solid solutions of decreasing lattice parameter as the Al content increases. • The absolute aluminum concentration increases the hardness and modulus of the quaternary solid solution. • Solid solution strengthening constituted the as main mechanism of the coating indentation hardness and modulus evolution.

Mechanical properties and low temperature degradation of 1.5Y-1.5Nd-TZP-alumina composites produced by intensive co-milling

In this study toughness of alumina toughened zirconia (ATZ) was improved by co-stabilization by shifting from co-precipitated yttria stabilized zirconia powder to yttria neodymia co-stabilized starting powders in which the stabilizers were introduced by intensive milling. Alumina contents were varied between 0.5 and 20 ​vol.-%. Test samples were consolidated by hot pressing.Microstructure, phase composition, mechanical properties and LTD were studied. The results show that alumina addition leads to an increase in hardness and to a moderate increase in strength. Decreasing toughness with increasing alumina content is coupled with reduction in transformability. Alumina shows no grain growth inhibiting effect, the grain size is dominated by sintering temperature. An increase of sintering temperature causes a decrease of tetragonality of the zirconia matrix despite a rise of cubic phase content. Samples sintered at 1300 ​°C and 1350 ​°C are extremely ageing resistant while samples sintered at 1400 ​°C irrespective of alumina content exhibit poor LTD performance.

The corrosion behavior and film properties of Al-containing high-entropy alloys in acidic solutions

Aluminum has shown promising application in reducing the high-entropy alloys’ weight and enhancing their mechanical properties. In this work, the impact of solid-solution aluminum on the corrosion behavior and film properties of FeCoCrNiAlx (x = 0.1, 0.3) high-entropy alloy in 0.5 M H2SO4 and 0.5 M HCl solutions was investigated by electrochemical measurement, Auger electron spectroscopy, and X-ray photoelectron spectroscopy. The results demonstrate that both of the high-entropy alloys exhibit an equiaxed grain structure with numerous annealing twins. FeCoCrNiAl0.3 alloy still remains the stable FCC substrate without any second phase precipitates. The increasing aluminum content can improve the corrosion resistance of FeCoCrNiAlx by simultaneously increasing Cr oxide content in the passive film and making it thicker in the H2SO4 solution. Nevertheless, the effect is negative in the HCl solution because chloride ions are inclined to combine with the Al-containing metastable ion complexes, which accelerates the dissolution of HEA.

Performance of the layered cobaltites in membrane mediated oxygen separation from air and methane partial oxidation

The performance of dense ceramics LnBaCo2–xAlxO6–δ, where Ln = Pr, Sm, and Gd, and x = 0.025 and 0.1, was studied at oxygen separation from the air and membrane-mediated catalytic partial oxidation of methane. The best oxygen permeability was observed for PrBaCo2–xAlxO6–δ at x =0.025. The increase of aluminum content and the decrease of the rare-earth size resulted in a fast decline of the oxygen separation efficiency. The oxygen flux is found to improve more than ten times at partial oxidation of methane (POM) with the selectivity for CO near 90%. The energy-dispersive X-ray spectroscopy (EDX) analysis gives evidence to phase separation effects in the membrane material after 800 h of the POM run.

Технология получения композиционных конгломератных порошков для плазменного напыления высокотемпературных защитных покрытий

Introduction. For parts of gas turbines operating under conditions of corrosion-erosion and intense wear, the most acceptable are compositions containing Ni, Co, Cr, Al, B, Y both in pure form and in the composition of compounds applied on the contact surface during thermal spraying. Modern integrated complexes obtained by combining dissimilar substances in the form of a single composition are promising. Such powders are obtained either by cladding or by conglomeration of finely dispersed starting components into a larger particle. The problem of developing and manufacturing plants for conglomeration of powders is urgent and practically important, since it makes it possible to obtain material for thermal spraying of coatings for high-temperature purposes. The aim of the work is to develop a technological scheme for obtaining powders of the required chemical composition with a given particle shape and size, intended for spraying high-temperature protective coatings. Materials and research methods. A technology is developed for the production of integrated powders for spraying coatings using the method of spray drying and subsequent sintering in vacuum or in an argon-hydrogen atmosphere, which avoids the loss of feedstock due to the return of fine and coarse fractions. A technology for preparing materials for spray drying and granulation is proposed. A gravity type aerodynamic classifier is designed and manufactured, which makes it possible to select automatically the powder fraction necessary for spraying the coating, as well as return the unwanted fraction for recycling. The morphology of the granular powder is determined using a TESCAN scanning electron microscope. The chemical composition of the resulting integrated complexes is determined by X-ray microanalysis on an OXFORD attachment. Results and discussion. The technological conditions for obtaining powders of a given size (40…100 µm) are established. It is shown that the shape of the conglomerate particles after spray drying is close to spherical. On the basis of a multifactor experiment, the optimization of the technological process for obtaining powders Ni-17Cr-10Al-1Y and Ni-22Cr-16Al-1Y with sizes up to 100 µm is performed. It is shown that when conglomerating powders with increased aluminum content (Ni-22Cr-16Al-1Y), it is necessary to take into account the exothermic reaction of nickel aluminide formation and dilute the mixture of initial components before sintering with the finished sintered powder. The resulting integrated complexes are characterized by high heat resistance; therefore they are designed and successfully used for plasma spraying of protective coatings for high-temperature purposes. Conclusions. A technology is developed for obtaining composite conglomerated powders Ni-17C-10Al-1Y and Ni-22Cr-16Al-1Y with particle sizes up to 100 µm and a shape close to spherical. A distinctive feature of this technology is that it avoids the loss of feedstock by returning fine and coarse fractions.

Forest Soil Cation Dynamics and Increases in Carbon on the Allegheny Plateau, PA, USA Following a Period of Strongly Declining Acid Deposition

Reductions in exchangeable calcium and magnesium and increase in exchangeable aluminum concentrations have been shown in soils impacted by acid deposition, including at four sites on the Allegheny Plateau, PA, USA, sampled in 1967 and 1997 during a period of peak deposition. We repeated sampling at these sites in 2017 to evaluate changes in soils during the more recent period when there has been a strong decline in acid deposition. The uppermost horizons, including the Oa and A horizons where humified organic matter transitions to mineral soil, were thicker, had higher concentrations of organic carbon and exchangeable calcium and magnesium, and lower concentrations of exchangeable aluminum in 2017 compared to 1997, approximating values measured in 1967. Below the Oa/A horizons, 2017 soil chemistry was more similar to the 1997 results, with some reduction of Ca in the recent measurements. These results suggest recovery of base cation–aluminum balance in surface horizons and may indicate a reduction of aluminum mobilization and increased efficiency of vegetation recycling of nutrients with decreased acid anion concentrations. These changes are consistent with a partial recovery from acid deposition. However, the increase in humified soil organic matter may also be affected by coincident increases in temperature and soil moisture.

Effects of aluminum content on the energy output characteristics of CL-20-based aluminized explosives in a closed vessel

In this paper, a series of experiments were performed to study the energy output characteristics of CL-20-based aluminized explosives in an explosion vessel. The influences of different aluminum mass contents on the shock wave pressure and the explosion power were systematically investigated. The results showed that the peak overpressure and the positive impulse of the initial shock wave decreased with the aluminum content increased from 10 to 30%. On the contrary, the quasi-static pressure increased. The deformation and damage degree of sealing steel plates of the explosion vessel decreased as the aluminum content increased. The analysis indicated that the maximum residual deflection of the steel plates mainly represented the energy of the initial shock wave. The explosion power of the CL-20-based aluminized explosives decreased with the increase in aluminum content, and this trend was more remarkable at a large charge mass. The contrast test with LiF showed that the energy released from the combustion of aluminum can improve the positive impulse of the initial shock wave and play a role in the deformation of steel plates.

Viscoelastic behavior of alkali and alkaline earth aluminophosphate glasses

• Viscoelasticity of alkali and alkaline-earth aluminphosphate glass was investigated. • Activation energy of stress relaxation changed with aluminum content. • Different change in two series would be due to existence of AlO 4 . The viscoelastic behavior of alkali and alkaline earth aluminophosphate glasses was studied. The energetic interpretation was based on the Arrhenius behavior of the relaxation modulus. With increasing aluminum content, the activation energy of the relaxation increased in the alkali series but decreased in the alkaline earth series. Dynamic viscoelasticity measurements revealed that the loss modulus, E ”(ω), showed a crossover of the relaxation process at the glass transition temperatures. The activation energy below the transition temperature was close to the energies of internal friction or ionic self-diffusion. The energy above the transition temperature corresponded to the dissociation energies of alkali-oxygen or alkaline earth-oxygen single bonds. The different behavior in the energy of the relaxation modulus between alkali and alkaline earth series was due to weak bonds caused by adding alkali ions and the formation of crosslinking by low-coordinate aluminum polyhedra because of the presence of alkaline earth ions.

The Effect of Aluminum on the Divorced Eutectic Transformation of MnS Inclusions

The mechanical properties of steels can be deteriorated by the formation of type II sulfide inclusions. The addition of alloying elements Al, C, and Si is generally considered to promote the transition from type II to type III sulfides. However, the mechanism of how alloying elements, especially Al, affect the transition is still unclear. In this work, the effect of aluminum on the divorced eutectic transformation of MnS inclusions was investigated. The research results show that most sulfides are type II MnS in micro-alloyed YF45MnV steel with Al concentration lower than 0.027 wt pct. The sulfides in the steel with Al concentration higher than 0.038 wt pct are type III MnS. The increase of aluminum content promotes the transition of sulfide morphology from the type II to type III, but increasing cooling rate can have the opposite effect. It is also found that an increase in Al content can significantly affect the equilibrium dissolved oxygen content and surface tension, but has little influence on the activity coefficient of S, precipitation temperature, initial S content in liquid steel, and solid fraction of the precipitation of MnS. High Al content can increase the interface energy between the liquid steel and MnS and promote the divorced eutectic transformation of MnS and form type III MnS.

Influence of Aluminum on Fatigue Strength of Solution-Strengthened Nodular Cast Iron

The fatigue strength of high silicon-alloyed nodular cast iron is influenced by casting defects and graphite precipitates. The literature as well as the findings of this work show that these microstructural constituents can be tailored by controlling silicon microsegregation. In addition, segregations also affect the ferritic matrix microstructure locally. In the present work, silicon segregations in high silicon-alloyed ductile iron are specifically manipulated by small additions of aluminum. It was demonstrated how the aluminum content affects a wide range of microstructural constituents across a variety of length scales. Specimens from alloys with small additions of aluminum were fabricated and tested by rotating bending. Results show that the fatigue strength can be increased compared to a reference alloy with no aluminum. Microstructure analysis as well as fractography were performed concluding that microstructural changes could be attributed to the increased aluminum content, which allows the fatigue properties to be tailored deliberately. However, according to the results of this study, the negative effect of aluminum on castability and graphite morphology limits the maximum content to approximately 0.2 wt.%.

Investigation on the Microstructure of ECAP-Processed Iron-Aluminium Alloys.

The present work deals with adjusting a fine-grained microstructure in iron-rich iron-aluminium alloys using the ECAP-process (Equal Channel Angular Pressing). Due to the limited formability of Fe-Al alloys with increased aluminium content, high forming temperatures and low forming speeds are required. Therefore, tool temperatures above 1100 °C are permanently needed to prevent cooling of the work pieces, which makes the design of the ECAP-process challenging. For the investigation, the Fe-Al work pieces were heated to the respective hot forming temperature in a chamber furnace and then formed in the ECAP tool at a constant punch speed of 5 mm/s. Besides the chemical composition (Fe9Al, Fe28Al and Fe38Al (at.%—Al)), the influences of a subsequent heat treatment and the holding time on the microstructure development were investigated. For this purpose, the average grain size of the microstructure was measured using the AGI (Average Grain Intercept) method and correlated with the aforementioned parameters. The results show that no significant grain refinement could be achieved with the parameters used, which is largely due to the high forming temperature significantly promoting grain growth. The holding times in the examined area do not have any influence on the grain refinement.

Influence of aluminium content on the microstructure and densification of spark plasma sintered nickel aluminium bronze

In this study, nickel aluminium bronze alloys (NAB) with appreciable densification and improved microhardness was consolidated via spark plasma sintering technique. The NAB alloy was synthesized from starting elemental powders comprised nickel (4 wt.%), aluminium (6, 8 & 10 wt.%) and copper using dry milling technique. Starting powders were homogeneously milled using gentle ball mill for 8 h at a speed of 150 rpm and a BPR of 10:1. Subsequently, the milled powders were consolidated using the spark plasma sintering technique at 750 °C under a compressive pressure of 50 MPa and rate of heating (100 °C/min). Furthermore, the powders and sintered alloys were characterized using SEM and XRD to ascertain the microstructural and phase evolutions during the synthesis of the NAB. The density and microhardness of the alloys were further investigated to ascertain the integrity of the sintered alloys. The results indicated that the increase in aluminium content resulted in the formation of intermetallic and beta phases on the alloy after sintering and the microhardness of the alloys improved with the increase in aluminium content.

Geological position and mineral composition of kyanite amphibolites of the Chupinskiy paragneiss belt (Belomorian province of Eastern Fennoscandia)

The Lyagkomina occurrence of kyanite amphibolites (the Belomorian Province of the Fennoscandian Shield) is confined to an amphibolite boudin among kyanite-garnet-biotite and garnet-biotite gneisses of the Chupa Sequence. The main rock types at the Lyagkomina occurrence are meso- and melanocratic garnet-kyanite amphibolites with large kyanite (more than 1 cm in length) and kyanite-garnet amphibolites with small kyanite. There are also leucocratic garnet-biotite-amphibole-plagioclase rocks with kyanite, melanocratic epidote-staurolite-amphibole rocks, zoisite plagioclasites with staurolite and kyanite. The country gneisses around the boudin were metasomatically altered: quartz disappears in kyanite gneisses, and amphibole appears in garnet-biotite gneisses. Calcic amphiboles in the kyanite amphibolites are represented by high-alumina tschermakite; biotite — by intermediate-alumina phlogopite; garnet belongs to the pyrope-almandine series with a high grossular content. Plagioclases have an intermediate and basic composition. Intermediate plagioclases are common in kyanite amphibolites without staurolite and in kyanite amphibolites with staurolite rims, while the basic plagioclases are found in staurolite amphibolites. Many rocks are characterized by reaction structures, representing the change of the mineral assemblages. Metasomatic zoning has been reconstructed in the occurrence with a regular sequence of the mineral assemblages: Hbl + Grt + Pl + Qtz ± Bt (garnet amphibolite) → Hbl + Grt + Pl + Ky + Qtz ± Bt → Hbl + Grt + Pl + Ky ± Bt → Hbl + Grt + Pl + Ky + St ± Bt → Hbl + Grt + Ky + Pl + St + Czo ± Bt → Hbl + Grt + Pl + St + Czo ± Bt → Hbl + St + Czo + Pl ± Bt. In the described series, the alumina content increases and the Mg content of the main rock-forming minerals decreases, and desilication of the rock occurs. The described mineral zoning was formed during metamorphism as a result of the reaction between the initial amphibolite and fluid flow in the shear zone (i. e., at synmetamorphic metasomatism). Petrological and isotope data indicate that the Lyagkomina kyanite amphibolites are genetically related to the occurrences of corundum-bearing rocks in the Belomorian Province of the Fennoscandian Shield.