Heterophase Inclusions Research Articles

PECULIARITIES OF CRACK FORMATION IN HETEROPHASE INCLUSIONS OF THE “EUTECTICS OF INCLUSION − MATRIX” TYPE

Purpose. The goal of the work was to study the peculiarities of crack nucleation in heterophase inclusions of the “eutectic inclusion − matrix” type during steel deformation. Methods. The research was carried out after deformation of samples from steels 08Yu, 12GS, 08kp, 09G2S, NB-57, 08GSYUTF in the temperature range of 20…1 200 °C with the speed of movement of grips 1 680 mm/min. The research methods were used − petrography, micro-X-ray spectral analysis (Cameca MS-4, Nanolab-7), optical microscopy (Neophot-21). Results. It is established that the variety of phases that make up heterophase inclusions of the type “eutectic of inclusion − matrix” leads to their different behavior under conditions of plastic deformation. It is shown that the nucleation of brittle or viscous microcracks occurs along the internal interfacial boundaries between the metal matrix and the second phase of the eutectic. It is determined that the nature of cracks is determined by the level of plasticity of the inclusion phases and the deformation temperature. It is shown that the critical degrees of deformation of the samples, at the achievement of which there were noticeable microcracks along the internal interfacial boundaries, depend on the temperature and nature of the phases of inclusions “eutectic of inclusion − matrix”. It is established that the values of critical degrees of deformation determine the level of cohesive strength of the internal interfacial boundaries in heterophase inclusions “inclusion − matrix eutectic”. Scientific novelty. Peculiarities of microcracking nucleation in heterophase inclusions of the “inclusion − matrix eutectic” type have been established. It is shown that the nature of microcracks formed along the interfacial boundaries depends on the temperature, level of plasticity and conditions of combination of brittle and plastic phases in inclusions of the “eutectic of inclusion − matrix” type, as well as on the deformation temperature. It is shown that the critical degrees of deformation of steels, when microcracks occurred along the inner interfacial boundaries, determine the cohesive strength of these boundaries and depend on the temperature and nature of the phases of inclusions such as “inclusion − matrix eutectic”. Practical significance. The use of the results obtained will make it possible to develop technologies for producing steels with regulated types of heterophase nonmetallic inclusions, which will significantly increase their technological and operational characteristics, as well as prevent the formation of various kinds of defects during the processing of steels by pressure and the operation of products.

ОСОБЛИВОСТІ НЕОДНОРІДНОСТІ ПЛАСТИЧНОЇ ДЕФОРМАЦІЇ ГЕТЕРОФАЗНИХ НЕМЕТАЛЕВИХ ВКЛЮЧЕНЬ В СТАЛЯХ

The nature and level of plasticity of microcomposite heterophase inclusions in steels under pressure treatment condition was investigated. Plastic phases in heterophase inclusions of various types under the conditions of hot and cold deformation of steels were investigated. It is shown that each type of inclusions, which are microcomposite formations in steels, is characterized by its own laws of the development of deformation processes, which are determined by their chemical and phase composition, structure, deformation capacity of inclusion phases. The generalized of the plastic behavior of heterophase inclusions of various types with a complex structure have been established and inhibitory effect of non-deformable inclusion phases on the behavior of plastic phases in a wide range of deformation temperatures of steels has been established. The peculiarities of the nature of plasticity of heterophase inclusions with different compositions and structures are discussed. The use of the obtained results will make it possible to develop technologies for obtaining steels with a regulated content and types of heterophase non-metallic inclusions, which will significantly increase their technological plasticity, as well as prevent the formation of various types of defects during pressure treatment of steels.

FEATURES OF THE CRACKS’ FORMATION IN HETEROPHASE INCLUSIONS OF THE “DISPERSED PHASES IN A NON-METALLIC MATRIX” TYPE

The purpose of the article − to study of crack nucleation features in heterophase inclusions of the “dispersed phases in a non-metallic matrix” type under the conditions of steels’ plastic deformation. Methods. The research was conducted after deformation for a number of different grades steel samples in the temperature range of 20...1 200 °С on Instron-1195 and IMASH-5C with special grippers, with a gripper movement speed of 1 680 mm/min. Research methods were used: petrography, micro-X-ray spectral analysis (Cameca MS-4, Nanolab-7), optical microscopy (Neophot-21). Results. It is shown that the variety of phases composing the heterophase inclusions "dispersed phases in non-metallic matrix" leads to their different behaviour under plastic deformation conditions. At the same time, the nucleation of brittle or viscous microcracks occurs along the internal interphase boundaries between the "non-metallic" matrix and the dispersed particles of the second phase. The cracks’ character near the inclusions determined by the plasticity level of “matri” and dispersed phases of inclusions and the deformation temperature are revealed. The determined critical degrees of samples’ deformation, upon reaching which appreciable microcracks along the internal interphase boundaries occurred, were depend on temperature and the nature of the “dispersed phases in a non-metallic matrix” inclusions. Scientific novelty. The features of microcracks nucleation associated with heterophase inclusions of the “dispersed phases in non-metallic matrix” type with different combination of brittle and plastic phases during steels’ deformation are determined. The types of microcracks occurring in inclusions of the “dispersed phases in the non-metallic matrix” type and the locations of their formation have been determined. It is shown that the values of the deformation critical degrees determine the level of cohesive strength for internal interphase boundaries in heterophase inclusions “dispersed phases in a non-metallic matrix” at different deformation temperatures. Practical value. The use of the obtained results will make it possible to develop technologies for producing steels with regulated types of non-metallic heterophase inclusions that will allow to increase significantly their technological and operational characteristics, and also to prevent the formation of various defects in the steels' treatment by pressure and the operation of products.

FEATURES OF THE CRACKS’ FORMATION IN HETEROPHASE INCLUSIONS OF THE “EUTECTICS OF INCLUSION – MATRIX” TYPE

The purpose of the article − to study of crack nucleation features in heterophase inclusions of the “eutectic of inclusion-matrix” type during steel deformation. Methods. The research was conducted after deformation for a number of different grades steel samples in the temperature range of 20...1 200 °С on Instron-1195 and IMASH-5C with special grippers, with a gripper movement speed of 1 680 mm/min. Research methods were used: petrography, micro-X-ray spectral analysis (Cameca MS-4, Nanolab-7), optical microscopy (Neophot-21). Results. It is found that the variety of phases composing the heterophase inclusions of the "eutectic of inclusion-matrix" type leads to their different behaviour under conditions of plastic deformation. It is shown that the nucleation of brittle or viscous microcracks occurs along the internal interfacial boundaries between the metal matrix and the second phase of the eutectic. It is defined that the cracks’ nature is determined by the plasticity level of the inclusion phases and the deformation temperature. It is shown that the critical degrees of samples’ deformation, at which appreciable microcracks along the internal interphase boundaries appeared, depend on the temperature and the nature of the inclusion phase “eutectic of inclusion – matrix”. It is found that the values of deformation critical degrees determine the level of cohesive strength for internal interphase boundaries in heterophase inclusions “eutectic of inclusion – matrix”. Scientific novelty. The features of microcracks nucleation in heterophase inclusions of the “eutectic of inclusion − matrix” type are determined. It is shown that the nature of the microcracks formed along the interphase boundaries depends on the temperature, plasticity level and combination conditions of brittle and plastic phases in inclusions of the “eutectic of inclusion − matrix” type as well as on the deformation temperature. It is shown that the critical degrees of steels deformation, when microcracks appeared along the internal interphase boundaries, determine the cohesive strength of these boundaries and depend on the temperature and the nature of the inclusion phase “eutectic of inclusion − matrix” type. Practical value. The use of the obtained results will make it possible to develop technologies for producing steels with regulated types of non-metallic heterophase inclusions that will allow to increase considerably their technological and operational characteristics, and also to prevent the formation of various defects during steel pressure treatment and product operation.

Suppression of impurities absorption and heterophase inclusions in Ge-As-S glasses

Strong absorption from the impurities and background scattering induced by heterophase inclusions are major issue in the applications of Ge-As-S glass in mid-infrared (MIR). Here, we report that, the absorption of impurities sourced from raw materials can be removed effectively by oxygen getters and hydrogen getters under static vacuum distillation, leading to almost disappearance of the absorption at 3.11 μm due to SH, <4.08 ppm at 4.01 μm due to SH and < 11.03 ppm at 7.5 μm due to As-O, respectively, in Ge10As28S62. The impurities of H2O and CO2 can be further eliminated to near zero by dynamic distillation. On the other hand, the heterophase inclusions, originating from raw materials of sulfur, arsenic and germanium, the silica-container and deoxidizer of Mg, can be eliminated thoroughly by dynamic distillation and optimized melting temperature. We draw the fibers using unpurified and purified glasses and found that, comparing with the fiber loss of 2.87 dB/m at unpurified glass, the optical loss can be decreased to about 1.86 dB/m in purified glass without any visible particles or heterophase inclusions. All the results pave the way of developing low loss Ge-As-S glass fiber for high power laser delivery.

CRACK INITIATION ALONG THE INTERPHASE BOUNDARIES OF THE “PHASE SIDE BY SIDE” TYPE HETEROPHASE INCLUSIONS

Purpose of research. Investigation into crack initiation features in heterophase inclusions of the “phase side by side” type during steel deformation. Methods. Destruction of various types heterophase inclusions is investigated during the deformation of samples from steels 08Ti, 08Al, 12MnSi, 08unk, 09Mn2Si, 08GSiAlTiV in the temperature range 20...1 200 °С. Samples of 08Ti and 08Al steels are subjected to tension, compression and bending, steel HB-57 − to tension and compression, steel 08unk, 08Cr, ATs45X ,ATs18XGT − to tension in vacuum at temperatures of 20...1 200 °С on experimental settings with special grips, which motion speed was 20 mm/min. Methods of investigation – petrography, X-ray microanalysis and optical microscopy were used. Results. It has been found that the diversity of phases composing the heterophase inclusions of the “phase side by side” type leads to their different behaviour under plastic deformation. The microcracks nitiation occurs along the internal interphase boundaries. Depending on the plasticity level of the phases composing the inclusion, these cracks can be brittle or ductile, which is also related to the effects of the deformation temperature. The features of microcracks initiation for different combinations of heterophase inclusions plastic and non-deformed phases of the “phase side by side” type are analysed. The interaction between heterophase inclusions of the “phase side by side” type and the steel matrix during deformation is discussed. Scientific novelty. The features of microcrack initiation related to heterophase inclusions of “phase side by side” type with different combination of brittle and plastic phases during steels deformation in a wide temperature range is determined. It was found that the microcracks initiation and spreading within inclusions “phase side by side” type occurs both in phases and along internal interphase boundaries. It is shown that the critical degrees of samples deformation, at which significant microcracks along the internal interphase boundaries occur, depend on the temperature and the inclusion phase. The critical degrees of samples deformation, upon reaching which significant microcracks occurred along the internal interphase boundaries, depended on the temperature and the nature of the “phase side by side” inclusions. The values of the critical degrees of deformation determine the level of cohesive strength of the internal interphase boundaries of the heterophase inclusions “phase side by side”. Practical significance. The use of obtained results will make it possible to develop technologies for producing steels with regulated types of heterophase non-metallic inclusions. This will substantially improve their technological and performance characteristics and prevent the various defects formation in the steel pressure treatment and the products operation.

THE PECULIARITIES OF THE FRACTURE OF HETEROPHASE INCLUSIONS OF THE TYPE "HIGH- MELTING PHASE SURROUNDED BY A LIGHT-MELTING SHELL" IN THE DEFORMATION OF STEELS

Purpose. The aim of the work was to study of the peculiarities of crack initiation in heterophase inclusions of the "high-melting phase surrounded by a low-melting shell" type during deformation of steels. Methods. The destruction of heterophase inclusions of various types was investigated during deformation of specimens from steels 08T, 08Yu, 12GS, 08kp, 09G2S, NB-57, 08GSYuTF in the temperature range 20...1 200 °C [1; 5]. Samples of steels were subjected to tension, compression and bending in vacuum at temperatures of 20…1 200 °C on Instron-1195 and IMASH-5C with special grippers, the movement speed of which was 20 mm / min. Methods of investigation –petrography and optical microscopy (Neophot-21) were used. Results. It was found that in the process of deformation of the steels in different temperature regimes, microcracks originating near heterophase inclusions of the "high-melting phase surrounded by low-melting shell" type can be brittle and ductile. In this case, the role of the level of plasticity of the phases making up the inclusion, which depends on the deformation temperature, is important. The features of microcrack initiation are shown for different combinations of plastic and non-deformable phases of inclusions. The interaction of heterophase inclusions and a steel matrix during deformation is analyzed. It has been established that the nucleation and growth of microcracks within inclusions of the "high-melting phase surrounded by a low-melting shell" type occurs both in the phases and along the internal interphase boundaries. Scientific novelty. Specific features of the initiation of microcracks associated with heterophase inclusions of the " high-melting phase surrounded by a low-melting shell" type, which have a different combination of brittle and plastic phases during deformation of steels, have been established. It is shown that the critical degrees of deformation of the samples, upon reaching which noticeable microcracks appeared along the internal interphase boundaries, depend on the temperature and the nature of the phases of the inclusions. Practical significance. The use of the results obtained will make it possible to develop technologies for producing steels with regulated types of heterophase nonmetallic inclusions, which will significantly increase their technological and operational characteristics, as well as prevent the formation of various kinds of defects during the processing of steels by pressure and the operation of products.

THE LEVEL OF PLASTICITY OF THE PHASES IN NON-METALLIC INCLUSIONS WITH A COMPLEX STRUCTURE

Purpose. It is necessary to study of the effect of heterophase inclusions on the technological ductility of steels for various purposes. The goal of the work was to study of the nature and level of plasticity of multiphase inclusions in steels under conditions of hot and cold deformation. Methods. Comprehensive methods for the study of heterophase non-metallic inclusions (metallographic, petrographic, X-ray microanalysis methods) were used. Results. Plastic phases in multiphase inclusions of different types under conditions of hot and cold deformation of steels were investigated. It is shown that each type of multiphase inclusions, which are microcomposite formations in steels, is characterized by its laws of development of deformation processes, which are determined by their chemical and phase composition, structure, deformation ability of the phases of inclusions. Scientific novelty. Peculiarities of plastic behavior of multiphase inclusions of different types are established. The inhibitory effect of non-deformable phases of inclusions on the deformability of plastic phases in a wide range of steel deformation temperatures is established. Peculiarities of the nature of plasticity of multiphase inclusions having different compositions and structure are discussed. Practical significance. Using the results obtained will allow developing technologies for producing steels with regulated content and types of multiphase non-metallic inclusions, which will significantly increase their technological plasticity, as well as prevent the formation of various kinds of defects during the processing of steels by pressure.

Plasticity Origin of Heterophase Inclusions at Steel Forming

Plasticity of heterophase nonmetallic inclusions of various types at hot and cold steel forming was studied. Transformation features of inclusions possessing different phase composition and structure were shown. Inhibiting effect of the second phase of inclusions on the formability of plastic phases at hot and cold strain of the steels was determined. Interaction features of the components of inclusion phases were studied, such as interactions in the inclusion–matrix interfaces and internal phase boundaries in inclusions. Features of the plasticity origin of heterophase inclusions possessing various compositions and structures were discussed.

The behaviour of heterophase inclusions “high-melting phase surrounding with low-melting cover” under steels pressure forming

Purpose. It is necessary to study of the effect of heterophase inclusions on the technological ductility of steels for various purposes. The goal of the work was to study the plasticity level of heterophase inclusions “high-melting phase surrounded with low-melting cover” during the processing of steels by pressure.Methods. Comprehensive methods for the study of heterophase non-metallic inclusions (metallographic, petrographic, X-ray microanalysis methods) were used. Results.It was found that heterophase inclusions “high-melting phase surrounded with low-melting cover” have different structures and phase compositions. The features of the plastic behavior of various phases in inclusions “high-melting phase surrounded with low-melting cover” with various combinations of phases were shown. The interaction of phases in the inclusions during the processing of steel by pressure was analyzed.Scientific novelty.The special features of the plastic behavior of heterophasic ones were identified, including the “high-melting phase, surrounded with low-melting cover” with steel sampling with a vice. It was shown that the process development of interphase rubbing at the boundaries of the included-matrix and at the internal boundaries of the inclusions was shown. The inverse phase inclusion at the third stage of deformation was presented. The possibility of transforming the inclusion of a “high-melting phase, surrounded with low-melting cover” in the process of hot and cold deformation when machining steel with a vice is shown. Practical significance.The results obtained will allow developing technologies for producing steels with regulated content and types of heterophase non-metallic inclusions, which will significantly increase their technological plasticity, as well as prevent the formation of various kinds of defects during the processing of steels by pressure.

THE BEHAVIOUR OF HETEROPHASE INCLUSIONS “PHASES ARE BESIDE” UNDER STEEL PRESSURE FORMING

Purpose. The technological ductility of steels is largely determined by the behavior of non-metallic inclusions at different deformation temperatures. The aim of the work was to study the shape change of heterophase inclusions of the “phases are beside” under different conditions of steel processing by pressure. Methods. Identification of inclusions of the “phases are beside” before and after deformation according to different modes was carried out by several methods: metallographic, petrographic, X-ray spectral analysis. Results. It has been established that the phase-mineralogical composition of the heterophase inclusions of the “phases are beside” determines the processes of their change under hot and cold deformation. The level of plasticity of the phases of inclusions determines the nature of their interaction between themselves and the steel matrix during their joint deformation. A different combination of phases in the inclusions of the “phases are beside” implies a different shape change of the inclusion as a whole during hot or cold rolling of steels. Scientific novelty. The shape-changing features of heterophase inclusions of the “phases are beside” during hot and cold deformation were established. The important role of interfacial friction processes was shown, which develops on sections of the inclusion-matrix boundaries (with different inclusion phases) and on the internal boundaries in inclusions whose phases have different plasticity. It was shown that the character of the shape change of the“phases are beside” inclusions is determined by the mutual influence of inclusions phases on their joint deformation. The possibility of transforming the inclusion of “phases are beside” in the process of hot and cold deformation when machining steel with a vice is shown. Practical significance. The obtained results of the study dedicated to features formation of heterophasic inclusions of the “phases are beside” can be used in the development of technologies for producing steels with the regulated content of heterophase non-metallic inclusions, including the type of “phases are beside”. These results contribute to solving important problems associated with improving the technological ductility of steels for various purposes, as well as preventing the formation of defects during the processing of steels by pressure.

Types and structure of heterophase inclusions in steels

Purpose. The problem of the influence of heterophase nonmetallic inclusions on the properties of steels is actual. The goal of the work was to study the main types and structures of heterophase nonmetallic inclusions in steels. Methods. Comprehensive methods for the study of heterophase non-metallic inclusions (metallographic, petrographic, X-ray microanalysis methods) were used. Results. It has been established that heterophase inclusions have different structure and phase composition. The features of various combinations of phases in microcomposite inclusions are shown. The main types of hetero-phase inclusions in steels are established. Scientific novelty. The structural features of heterophase inclusions in steels are established. A classification of microcomposite heterophasic inclusions is proposed: inclusions of the first type “high-melting phase surrounding with low-melting cover”; the inclusion of the second type of “phases are beside”; the inclusion of the third type of “eutectics”; Inclusions of the fourth type “dispersed phases in a non-metallic matrix”; inclusions of the fifth type "eutectics inclusion-matrix". Practical significance. The use of the obtained results will make it possible to develop technologies for the production of steels with regulated content and types of heterophase non-metallic inclusions, which will significantly improve their technological, mechanical and operational properties.

Experimental precision study of types and of the chemical composition of nonmetallic inclusions in radial section of the railway axis by the method of the electronic microscopy and x-ray spectral microanalysis

Purpose. Investigation of the structure and composition of non-metallic inclusions in the radial section of the draft railway axis obtained from continuously cast billets. Methodology. Studies were conducted on samples of steel EA1N using electron microscopy of X-ray spectroscopy analysis. Results. It has been established that during cooling of the melt and crystallization of the metal of a continuously cast billet, inclusions close in composition to quasi-equilibrium states of binary and ternary oxide systems are formed. Originality. The structures and composition of heterophase inclusions formed in the central part by spinel MgO * Al2O3 with the (Ca, Mn) S sulfide phase shell are identified. Practical value. The results of the study determine the modes of deoxidation and alloying of the axial metal during out-of-furnace treatment at LF and VD.

Heterophase inclusions as a source of non-selective optical losses in high-purity chalcogenide and tellurite glasses for fiber optics

The results of investigation of the impurity and phase inclusions as sources of non-selective losses in high-purity chalcogenide and tellurite glasses are reported. Extinction on the SiO2 inclusions is shown to be responsible for non-selective losses in the chalcogenide glasses obtained by direct synthesis from elements in quartz equipment. Optimization of the temperature/duration conditions of the synthesis makes it possible to decrease these losses. The problem of achieving the theoretical minimum of optical loss in the glasses prone to crystallization is considered. The minimal scattering loss in such glasses can be limited not only by “freezing” fluctuations but also by the phase inhomogeneity of the glasses. A substantial contribution of the phase inclusions to optical losses is demonstrated on the example of high-purity tellurite glasses. The scattering in highly homogeneous samples of these glasses appears to be two orders of magnitude higher than the known theoretical value for scattering on “freezing” fluctuations.

Influence of the preparation technique on the optical properties and content of heterophase inclusions of AS_2S_3 chalcogenide glasses

Bulk samples of As-S chalcogenide glasses were prepared by an interaction of vapors of volatile precursors in low-temperature non-equilibrium plasma discharge (plasma enhanced chemical vapor deposition (PECVD process)). Elemental arsenic and sulfur (As + S), and arsenic monosulfide and sulfur (As4S4 + S) were used as initial substances. In parallel, the As-S bulk samples were synthesized by “traditional” melting of the initial substances in the evacuated quartz ampoule from the same precursors. The optical properties of the bulk samples were compared. The exhausted gas mixtures were analyzed to clarify the difference in carbon impurities content. 3D laser ultra microscopy was used to determine the content of heterophase inclusions in the samples.

Adhesion mechanism of destruction of silica-glass surface during the preparation and treatment of optical glassy arsenic Chalcogenides

Adhesion of As–S and As–Se glasses to silica glass is studied by means of the steady detachment method. The results demonstrate that the adhesion strength of the boundary of solid phases increases with the content of chalcogens in the composition of glass. It is found that adhesion of arsenic sulfide glasses with sulfur content over 65% to silica glass exceeds the tensile strength of the silica glass during the process of solidification and annealing of chalcogenide preforms. The adhesion of arsenic chalcogenides to silica glass is determined to be the reason of chalcogenide glass contamination by heterophase inclusions.

Nature of heterophase inclusions in high-purity optical fiber materials as studied with 3D laser ultramicroscopy

3D laser ultramicroscopy (3D LUM) is intended specially for determining the concentration and size distribution of submicron inclusions in the bulk samples of high-purity materials for visible and IR fiber optics. In this work the 3D LUM technique is shown to be able to identify the nature of individual inclusions detected. The measurement of the light scattered by an inclusion at a varied probe beam wavelength and polarization and at a varied scattered light collection angle makes it possible to determine the inclusion refractive index. The 3D LUM possibilities are illustrated by the example of studying the inclusion nature in the As2S3 glass samples prepared by the direct synthesis from elements in a quartz container at elevated temperatures.

3D laser ultramicroscopy: A method for nondestructive characterization of micro- and nanoinclusions in high-purity materials for fiber and power optics

This paper describes a 3D laser ultramicroscopy technique and apparatus for the nondestructive characterization of heterophase inclusions in bulk high-purity materials for fiber and power optics. In this technique, the concentration and size of inclusions undetectable by optical microscopy are determined using CCD detection of the light scattered by them in a direction normal to the incident laser beam at wavelengths from 0.63 to 0.98 μm. The detection limit of the technique in terms of inclusion size is n × (10–100) nm, the range of detectable number concentrations is 1–1011 cm−3, and the scan depth in the sample is ∼1 cm. Its performance has been evaluated using test systems. The potential of the technique is illustrated by the dispersion analysis of promising materials for IR fiber-optic applications.

High-purity chalcogenide glasses for fiber optics

The data on the present degree of purity of chalcogenide glasses for fiber optics, on their methods of production and on the properties, which are essential for their actual application, are generalized. The content of limiting impurities in the best samples of chalcogenide glasses is 10–100 ppb wt.; of heterophase inclusions with size of about 100 nm is less than 103 cm−3. On the basis of chalcogenide glasses the multimode and single mode optical fibers are produced with technical and operation characteristics sufficient for a number of actual applications. The minimum optical losses of 12–14 dB/km at 3–5 µm are attained in the optical fiber from arsenic-sulfide glass. The level of losses in standard chalcogenide optical fibers is 50–300 dB/km in 2–9 µm spectral range. The factors, affecting the optical absorption of glasses and optical fibers, are analyzed, and the main directions in further development of chalcogenide glasses as the materials for fiber optics are considered.

Heterophase inclusions and dissolved impurities in Ge 25Sb 10S 65 glass

The impurity content and microhomogeneity of Ge 25Sb 10S 65 glass samples, prepared by direct synthesis from elements, were investigated. It was shown that the increase in temperature of synthesis of the glass-forming melt resulted in the increase of the content of impurities of H, Na, Al, Si, K, Ca and transition metals in the prepared glasses. The glasses from the melt, subjected to chemical-distillation purification, were characterized by the low content of gas-forming impurities and the increased content of Al, Si and Cl. The glasses contained heterophase impurity inclusions mainly consisting of SiO 2, and their concentration and size depended on the conditions of glass preparation. The impurity content in the purest glasses was as follows: oxygen – <0.5 ppm wt, carbon – <5 ppm wt, hydrogen – 0.1 ppm wt, Si – <1 ppm wt, transition metals – <0.25 ppm wt, heterophase impurity inclusions with sizes larger than 80 nm – <10 2 cm 3. It was shown that heterophase impurity inclusions behaved as the centers of glass crystallization.