STUDY OF CONSOLIDATION FEATURES FOR FRAGMENTALLY NANOSTRUCTURED HARD METAL COMPOSITES

Толық мәтін

Introduction. The analysis of accumulated informa- tion on scientific research in the field of new structures and hard-alloy composites manufacturing techniques de- velopment, production practice and application of various functional purpose products shows that special attention is paid to the use of powder materials components in a com- posite structure in the nanocrystalline state. The conventional global trend in the hard-alloy com- posites structure and properties improving is formation in them a superfine-grained structure with carbide phase sizes less than 300-400 nanometers. The problems of hard alloys quality improvement can be efficiently solved due to their nanostructuring by tungsten carbide nanodi- mensional powders use. It is well known that when using traditional methods of consolidation for obtaining high density of a sintered composite, high temperature and sintering holding time are necessary and lead to the initial sizes increase and to carbide grains growth [1-4]. Simul- taneous use of nano and submicrocrystalline carbides and alloying additives of grain growth inhibitors of the main phase nanoparticles can be considered as the most per- spective direction of nanostructured hard alloys with the increased hardness, durability and crack resistance pro- duction, which has to increase product endurance under conditions of heavy shock, thermomechanical loading [5] The main inhibitors are chrome carbides, vanadium, nio- bium, tantalum, titanium. Doping is carried out by various methods, for example, such as chemical, mechanical (high-energy spherical grind), etc. [3]. Forming the com- plex carbides with the main carbide phase or being dis- solved in cobalt, alloying elements influence not only on a microstructure, but also on mechanical and operational characteristics of an alloy [6-8]. A preliminary coating layer binding on carbides, i. e. producing composition powders in various ways, such as dusting, mechanical coating, coprecipitation, consecutive chemical reactions, two-stage processing, etc. can be an efficient processing method as well. The coating of car- bide particles with a binding layer is the starting method which allows to get volumetric billet maintaining the unique properties of initial nanopowders [9-11]. Matrix solid phase and covering-binding material are initially homogeneously distributed on the volume of a composite particle, so the properties uniformity of initial powders structure fragments is relayed on all composite volume. Nanodimensional cobalt film presence on carbides pow- ders provides sintering temperature decrease and in com- bination with high speeds of heating and the existence of inhibiting nanoparticles additives in the structure prevents carbide grains growth [3; 12-15]. Additional modifying by additives of nanoparticles provides the increase in binding durability and the level of physicomechanical properties of a composite in general. Such polyphase fragmentary nanostructured composite is characterized by additional heterogeneity determined by distinctions of the sizes and resilient properties of phases [2]. The range of such nanostructured hard metals possible use will only extend as such modifying changes the surface, chemical and reactionary processes at homogenization and as a result, structural parameters and properties of a composite in general. Materials and methods. The morphology and microstructure of powders and sintered materials were investigated with the scanning submicroscopy (SEM) of JEOL JSM-7001F use. A particle size distribution of initial and mixed powders were defined by the method of laser diffraction SALD-7101 Shimadzu of the scanning supermicroscope. Samples microstructure was investi- gated on polished surfaces by means of scanning electron microscopes Hitachi “TM1000” and JEOL JSM-7500FA. The structure and the nature of fracture surfaces were analyzed with the JAMP 9500F microscope use. The X-ray diffraction analysis was carried out on the D8 ADVANCE device. Mechanical propeties determination was performed: Vickers hardness of HV30 with a hard- ness gage (ABK-A, Akashi) use at 30 kgfs loading; crack resistance K1C dimpling by the Palmkvista method; durability by the three-point bending method on the Shi- madzu AG-IS 100 kN; studying of wear-resistance accord- ing to the ASTM B611-85 standard. The nanopowders received by the shock-wave synthe- sis method or the method of electroexplosion were used as additives for hard alloys modifying. The powders morphology is shown on fig. 1, average particle size in the range from 0.067-of 0.1 microns for Al2O3 (a, b); 0.08 microns for ZrO2 (Y2O3). Composition powders (WC-Co) obtained by complex application of chemical and microwave synthesis methods [10] with 0.2-0.4 mi- crons size (fig. 1, c). Results and discussion. Hard-alloy composites investigated in the work are composite materials, hetero- geneous in structure, at least, with one phase showing nanomaterial properties. When developing structures, manufacturing techniques and numerical assessment methods of new three-phase hard-alloy composites gen- eration composites formed by a combination of carbides grains (including plated by a binding metal layer), actu- ally binding with the distributed on its volume modifying nanoadditives of oxides, nitrides proceeded from the fol- lowing assumptions and prerequisites: - when sintering the prevention of carbide grain growth at the expense of nanoparticles inhibitors additives is provided; - the distribution of the main phases (a carbide basis, binding, and the nanoparticles distributed on binding vol- ume nanoparticles) is homogeneous, uniform in structure; - submicronic carbide grains are located at a well pre- dictable distance therefore the package density of a three- phase composite can be regulated (simulated) proceeding from a ratio of micron carbide volume fractions (Vm) and nanodispersible (Vf) fraction and their average sizes (dm, df); - when modelihg it is necessary to consider differences in a kinetics of mass transfer and reactivity of phase com- ponents in a sintering process. In works [13-15] it was shown that the effectiveness of hard alloys modifying by Al2O3f nanoparticles essen- tially depends on sizes, concentration and volume frac- tions of all composite WC-Co-Al2O3(ZrO2) components. At the random nature of void filling between carbide grains various structural fragments created by oxidecoated particles which have various degree of contact and internal microporosity can be formed. Conditionally fragments between carbide grains can be presented in the form of three main types of structures - their analytical (model) description compared to the results of the micro- structure experiment studies and properties results are given below. 1. The single isolated inclusions of nanoparticles. At small concentration of nanoparticles additives in the local volume of a cobalt layer the fragments presented in fig. 2 are formed. a b c Fig. 1. SEM nanopoweder morphology: a - aluminum oxide; b - circonium oxide; c - tungsten carbide composite particles coated with Co-layer (WC-Co) Рис. 1. SEM-морфология нанопорошков: а - оксид алюминия; б - оксид циркония; в - композитные частицы карбида вольфрама, покрытые слоем кобальта (WC-Co) a b c d Fig. 2. Geometric model of a hard alloy modified by nanoparticles: а - structure (fracture) fragment between carbide grains of a hard-alloy composite including Al2O3 nanoparticles; b - microstructure scheme; c, d - single volumes of cobalt binding Рис. 2. Геометрическая модель твердого сплава, модифицированного наночастицами: а - фрагмент структуры (излома) между карбидными зернами твердосплавного композита с включениями наночастиц Al2O3; б - схема микроструктуры; в, г - единичные объемы кобальтового связующего 1 Realization of this kind of fragments a WC-Co- nanoparticle composites structures is optimum from the point of view of the known mechanisms of dispersion metals hardening [2; 15]. Injected into a binding layer isolated and statistically uniformly distributed nanoparti- cles promote decrease of its thickness λэфф = f (l1, l2, n2) (fig. 2, а-c), which has to provide an increase of binding durability and, as result, hard-alloy composites in general according to mechanics of phases provisions. The efficient thickness of a cobalt layer choice λэфф was made on the basis of probability approach on the model more detailed described in [13-15] and various optional versions of a crack distribution through binding layers by width of l1, l2, l3, which sizes depend on nanoparticles additives con- tents and sizes. At the same time it was supposed that the material in unit volume of a cobalt binding (l 3) between carbide grains modified by nanoparticles, is dispersiblly strengthened according to the known Orovana mecha- nisms, i. e. durability of such fragment of the binding material modified by nanoparticlesadditives above, than at basic material cobalt: 0,25 % on weight, not only dispersiblly strengthen a cobalt layer (Hμ microhardness, measured by the micron- anohardness testing method, increases up to 22.01 GPa), but also provide flexure strength increase (to 25 %) - crack resistance according to Palmkvista (up to 50 %) (fig. 3), decrease in an abraser wear ~ 1.5 times. Mini- mum values of a wear are observed approximately in the same areas of additives (~ 0.25 % of masses.), which pro- vide durability increase.Tthe offered model calculations results show satisfactory convergence of calculation datas with experimental (fig. 3) [18]. Additional contribution to material wear resistancel increase is brought, apparently, by the increased resilience to an attrition of the aiuminium oxide itself (Hμ Al2O3 - 18-20 GPа). Substantially increase in the common level of strength properties is explained by the inhibiting effect of nanoparticles additives, the average size of carbide grain monotonically decreases with increase in their con- centration [19]. Material hardness and density values do not differ significantly from basic material and are at the level: but values of a microhardness of binding layer s¢B = 480 + 1550 , а l¢ = l l¢ эфф . (1) material - cobalt, which was estimated by means of nanomicrohardness gage increase as the known effect The destruction viscosity (crack resistance) of such fragmentary nanostructured hard-alloy composite can be determined by the formulas offered in works [16; 17] and adapted to the hard-facing alloys modified by nanoparti- cles: 1 ïì R × (l + dm ) × s¢B ×Vm × E ¢ ïü2 of dispersible hardening at the level of structure fragments is implemented (Co - Al2O3), slightly different. 2. Agglomerates from nanoparticles. Electronic and microscopic research shows that actual parameters of a hard-alloy composite microstructure differ from the geometrical model presented in item 1. It is quite under- standable on the assumption of physical reasons. At K1c = í ïî C1 ý , (2) ï þ increase in nanoparticles concentration in local volumes because of poor uniformity of components interfusing, where R - empirical reduction coefficient; dm - the aver- age size of carbide grain; Vm -volume ratio of carbide fraction; Е′ - the given elastic modulus; С1 - contact ability of carbide edges. The results of calculations for the offered model show satisfactory convergence of calculation data with the experimental [14]. By the experimental methods it was determined that ceramics nanoparticles Al2O3f in the quantity of 0,05- their contact ability degree increases and there occurs a formation of units with developed internal microporosity. During a unequigranular hard-alloy composites sintering process, the change of interphase energy happens first of all due to nanodisperse phases specific surface area decrease that can be followed by their agglomerating to larger micron formations and possible subsequent coagu- lation (fig. 4). Fig. 3. Nanoparticles size (d2) vs crack resistance (К1С) of WC-Co - nano Al2O3 composite: (· - calculation; □ - experiment) and wear rate Рис. 3. Влияние размера наночастиц (d2) на трещиностойкость (К1С) композита WC-Co - нано-Al2O3:(· - расчет; □ - эксперимент) и интенсивность износа However the noted structural metamorphoses are, to some extent, inevitable at traditional widely applicable in hard alloys production mixture-preparation methods. When reaching critical concentration of some nanoparticles and emergence of pressure between carbide grains at a liquid-phase sintering, manifestation of self- organization effects is revealed - a volume space struc- tural grid formation. Its basic elements are, apparently, contacts between nanoparticles and the nanoparticles in total forming the exact regular space cells with sizes of 100 nanometers in total (fig. 5, b). The agglomerates formed by ceramics nanoparticles become nanostructured i. e. pass into a totally new state. Emergence of such space fragments and transitions from free-dispersible to the bound-dispersible (aggregated) systems also a composite properties change. It can be explained on the basis of the well-known physical principles of ultradispersion medi- ums sintering theory, including nanostructural hard alloys [1-5; 20]. The existence of such fragments is illustrated by the results of a microstructure research (fig. 5). Be- sides, there can be formed crystal grains of α-phase Al2O3 inclusions (fig. 5, a), micron sizes, formed at the in- creased compounds density of a nanophase and as a result of sufficiently high pressures action in the intercarbide space during a sintering process (about 1370 ºС sintering point is enough for nano Al2O3 crystallization). 3. Unequigranular heterogeneous structure. The actual microstructure of the hard-alloy composites modi- fied by nanoparticles is heterogeneous, nonuniform on distribution and morphology of the additional oxide- coated phase created from nanoparticles. Formation of various types of structures (item 1, 2) can occurs at the same time on different mechanisms depending on various nanoparticles concentration in local volumes between the main carbide phase grains. During a sintering process various competing homogenization processes are implemented, their transformations also occur. It is con- firmed by the results of own microstructure electronic and microscopic research and of other authors data [1-4; 21]. Typical images of fragmentary nanostructured materials from polished surfaces of samples are provided in fig. 5, 6. a b Fig. 4. Nanoparticles distribution within hard-alloy composite WC-Co-Al2O3 (nano): a - concept scheme; b - microstructure fragment Рис. 4. Распределение наночастиц в структуре твердосплавного композита WC-Co-Al2O3 (нано): а - принципиальная схема; б - фрагмент микроструктуры Spectrum O Al W а b Fig. 5. Evolution of agglomerate structures from nanoparticles: а - crystallites; b - quasi-nanostructured fragment Рис. 5. Эволюция структуры агломератов из наночастиц: а - кристаллиты; б - квазинаноструктурированный фрагмент On the microscopic (micron) level statistically uni- formly distributed on material volume basis structural fragments in total (combination) form a new composite of a more complex level. The additional heterogeneity caused by distinctions of resilient phases characteristics describes such polyphase composite. It is revealed in inhomogeneity of a strain-srtess state at a liquid-phase sintering when manufacturing (at phase boundaries, in the course of contraction, consolidation) and at external mechanical impact on the compacted material. In particular, it is confirmed by material destruction viscosity research data according to the Palmkvista method in combination with a microstructure study. Cracks which are formed in the material as a result of an indentor (a diamond pyramid of Vikkers) introduction, draw attention essentially because they are potential carriers of indirect information on durability, operational material resistance, reflect changes in destruction mechanisms corresponding to various types of structure (fig. 2, 4). The crack which moves (propagates) mainly on WC interface boundaries - WC, WC-Co slows down (fig. 7, а, b), relaxes on nanoparticles Al2O3, ZrO2 dispersible inclusions, or on their conglomerates (fig. 7, c) distributed on cobalt layers volume. It is necessary to emphasize in this regard that emer- gence of discrete cracks approximately corresponds to the area of particles additives up to 0.2 % of masses. Similar changes in destruction mechanisms of the hard-alloy nanostructured composites at cracks propagation are indi- cated in research results [22; 23]. Thus, combining phase components sizes and proper- ties of in such heterogeneous composite, the energy of destruction increase (increase in trajectory length of an intercrystalline crack) is provided [24]. Despite structure inhomogeneity of an actual three-phase composite and existence of various types of fragments, the common in- tegral level of physicomechanical properties in the field of optimum additives increases research [14; 18]. 4. Polydisperse material on the basis of composite powders. Based on the positive experimental results and the discovered features of heterophase hard-alloy compos- ites structure formation, the geometrical model (fig. 2) also explicitly described in works [14], was specified and corrected, taking into account the known and new results of calculated and experimental studies of bimodal and polymodal disperse system package density as well. The offered specified stereological model is quadruple contacting in threes same size composite matrix particles (WC-Со). Carbide phase particles during modeling are conditionally accepted to be spherical. The centers of these spheres are tops of a tetrahedron which edges are formed by radiuses of Ri (fig. 8). On the basis of the conducted experimental studies the specified stereological model is offered [25]. During its realization the maximal package density and uniformity of composite phase components relative distributionis are provided. The modifying additives of nanoparticles homogeneously distributed in a binding layer promote its thickness decrease λэфф = f(l1, l2, n2) (fig. 8, а-c) that according to a geometrical model (p. 2.1) has to provide an increase of binding durability and as a result, a hard- alloy composite in general. A single volume (Vc) of such structure fr agme nt with a particles bimodal distribution by sizes ( dm , d f ) can be defined proceeding from the ratio: Vc = Nmvm + vp, where Nm - a number of carbide particles; νm - the average volume of carbide particles. Voidage (vp) between carbide particles proceeding from the known stereology provisions can be accepted equal to vp = 0.20776 (dm / 2)3. As a way of pressing density increase it is offered to enter tfa nano phase νf additional volume equal to the volume of voids, i. e vp = Nf νf. This condition is actually impracticable as the secondary nanoparticles dense packing forms own voids of vpf (fig. 8, b), i. e. Nf has to be reduced to Nf* by the volume of vpf which is offered to equate to the volume ratio of metal binding vb = vpf = = 0.20776 (df /2)3 (the quantity of Nf* particles can be calculated by analogy proceeding from the ratios given above). With this approach to the solution of a composite structure model operation problem its maximal density is provided. Подпись: Spectrum C O Al Co W Spectrum 1 13.40 3.65 1.17 74.6 7.25 Spectrum 2 - 58.94 37.08 0.71 3.27 Spectrum 3 - 57.02 31.32 6.16 5.50 Spectrum 4 46.03 - - - 53.9 Fig 6. Forming of different structure fragments within heterogeneous hard-alloy composite Рис. 6. Формирование различных фрагментов структуры гетерогенного твердосплавного композита а b Fig. 7. Crack-propagation pattern due to the Vickers Pyramid dint: (a, b) - crack stopping at nanoparticle in- clusions (binder metal on the surface of polished section has been removed by etching); (c) stress relaxation in the front of crack propagation (contrasting etching of the section) Подпись: d(WC-Co) dWC Рис. 7. Характер распространения трещин от угла отпечатка пирамидки Виккерса: а, б - торможение трещины на включениях наночастиц (металл связки с поверхности полированного шлифа удален травлением); в - релаксация напряжений во фронте распространения трещины (контрастное травление шлифа) а b c Fig. 8. Stereological model of a three-phase composite: а - packing scheme; b - geometric model of the system dm(WC-Co) - nano- agents of ceramic df (Al2O3f, ZrO2f); c - three-phase structure parameters Рис. 8. Стереологическая модель трехфазного композита: а - схема упаковки; б - геометрическая модель системы dm(WC-Co) - нанодобавки керамики df (Al2O3f , ZrO2f); в - параметры трехфазной структуры Composite powders use is expedient, proceeding as well from physical reasons as well, because the existence of a thin-layer binding activates the processes of consoli- dation, mass transfer at the lower sintering point. The formation condition in a monolayer sintering process (binding - nanoparticles) and at the same time demands obtaining a hard alloy dense structure from composite powders (WC-Co) demands at “sewing together” of different models, considered in the work, realizations of the following ratios: Nm 3 β0· d + d = N ·ν + N ·ν - N ·ν , (3) bide space is filled with a composition powders coat layer (Co-WC) and additives of oxides nanoparticles (fig. 10, a). Efficiently influence the processes of such hard alloys structurization is also possible due to the use of the alter- nate methods of consolidation, intensive plastic and a shear deformation at mixtures formation (for example extrusion or rolling), stage-by-stage stepped heating with withstanding temperatures corresponding to the consolida- tion mechanisms change, the so-called operated sintering, high-speed and low-temperature compression sintering, electrospark plasma sintering, methods of thermome- chanical cycling (which are widely applied for steels and å m f i=1 m m m ρ f f alloys) and thermomechanical ultrasound processing. The physical sense of such influence is that in a peculiar mate- ( ) νh = 4π((Rm + h)3 - Rm3)/3Rm3, (4) where β0 - the coefficient defining a form of structure; h - layer thickness of a nanoparticles monolayer with df size; νh - layer volume with h thickness. Meanwhile, the numerical values of parameters of a composition particle and coat layer thickness from metal binding on composite carbides powders can be defined from a simple ratio: V sh rial “buildup”, structurization processes activation at con- solidation, decrease in the average size and carbide grains contact ability. Finally it will allow to reduce a sintering point and to create and keep more fine-grained structure of a hard alloy composite WC-Co-Al2O3, WC-Co-ZrO2. Studying of alloys consolidation features on the basis of submicronic composite powders (WC-Co) with initial sizes of carbide grain about 0.8 microns show that inten- sive contraction occurs already at a temperature 1320- h = , (5) 1350 ºС that is on hard-phase sintering stages. These data Vcm dm where Vcm - composite particle volume. On the basis of a new stereological model (fig. 8) es- timating calculations of nanoparticles additives necessary to generate pressings with the greatest package density were made. For particle sizes of a composite carbide phase with sizes in the range of dm (WC) from 0.3 to 0.8 microns and the sizes of ceramic nanoparticles df from 0.008 to 0.1 microns used in the experimental part of work the necessary concentration of nanoparticles addi- tives in mixture composition made Vf = 0.30 or about 3 % of masses. The results of experimental studies allowed to specify calculated formulas by means of semiempirical coefficients and to define optimum concentration of nano- particles additives in the range from 1 to 3 % of masses. The use of composition submicronic powders (WC-Co) received by various methods [9-11] can be the way of im- plementation of this kind of heterogeneous structures with the maximal package density and at the same time providing high uniformity of the relative composite phase components distribution. In the experimental part of work the composi- tion powders received a traditional chemical deposition on the carbon carrier in combination with microwave influence [10] (fig. 9) are used. X-ray phase analysis results showed that the made powder hard-alloy mixtures, alloyed by oxides nanoparti- cles in the number of 1 %, have the average size of tung- sten carbide crystal grains about 150 nanometers. Alloying additive content Increase from 1 to 3 % finds a tendency to decrease of nanoparticles coalescence effects of tung- sten carbide when processing in the spherical activator and US- activation [26]. In case of composition layer powders (WC-Co) of the submicronic sizes as a basis and additional alloying of inhibitors nanoparticles additives Al2O3 use, the structure created as a result of a simple hard alloy sintering consists of almost isolated carbide grains partially blocked at the expense of a cobalt ductile coat (fig. 10, a). The intercarare well consistent with the results given in works [1; 3]. In temperatures intervals from 1370-1420 ºС there is a partial grain recrystallization of the phase WC to the sizes of 1.5 microns. However at the same time the submi- cronic carbide phase of initial composite powders in com- bination with additives of oxides nanoparticles (fig. 10, a) remains in a cobalt layer between these carbide grains. Finally, positive structural changes provide additional increase of a strength properties level. Additional experi- mental studies conducted in collaboration with National Research Tomsk Polytechnic University (TPU) [26] dem- onstrate that critical threshold concentration cut-off levels of nanoparticles additives in the nanostructured hard-alloy composites WC-Co--nаnо Al2O3(ZrO2), received by the electrospark plasma sintering method, is 3 % of masses. In total the calculated results (on the model) and the experimental studies (methods of a scanning electron microscopy in combination with the elememt-by-element analysis use and standard methods of physical tests) allowed to realize microstructure parameters with rela- tively high distribution uniformity of phase components (tungsten carbides grains, a metal binding layer and modi- fying additives of nanoparticles) on a volume of a hard- alloy composite (fig. 11). Increase in content of alloying additive to 3 % leads to slowing down of grain growth processes: the average size of coherent scattering area (CSA) for these samples was in the range from 151 to 163 nanometer (fig. 12, b). The average size of CSA cobalt bindings according to X-ray analysis does not exceed 22 nanometers [26]. Thus, the received results demonstrate positive influ- ence of nanoparticles additives on properties of reference hard alloys (see the table) that is explained, first of all, by their structural parameters change. Formation of nanostructural fragments in the volume of a metal cobalt layer provides decrease to the submi- cronic sizes of its thickness between carbide grains, the effect known in materials science as the effect of dis- persible hardening, is implemented. а b Подпись: All results in atomic % Spectrum C O Co W Spectrum 1 76.22 3.35 2.09 18.34 Spectrum 2 61.08 3.93 7.11 27.88 Spectrum 3 86.56 1.48 1.35 10.61 Spectrum 4 73.87 3.36 1.61 21.16 Spectrum 5 73.22 2.61 1.83 22.35 Spectrum 6 80.20 3.71 3.19 12.91 c Fig. 9. WC-Co composite powders morphology: а - microwave synthesis composite powders; b - results of powders elementary analysis; c - powders (WC-Co) produced by chemical method Рис. 9. Морфология композитных порошков WC-Co: а - композитные порошки микроволнового синтеза; б - результаты их эле- ментного анализа; в - порошки (WC-Co), полученные химическим методом Spectrum C O Co Al W Spectrum 1 24.94 10.44 8.44 1.44 54.74 Spectrum 2 16.89 - 2.56 2.20 78.35 а b Fig. 10. Microstructure of hard alloys obtained from composite powders WC-Co: a - SEM; b - elementary analysis results Рис. 10. Микроструктура твердых сплавов полученных из композитных порошков WC-Co: а - SEM; б - результаты элементного анализа Fig. 11. Electron microscope images: nanostructured hard alloy, EDS map for local deposit of alloying constituent on the surface of hard-alloy composite produced on the basis of micron carbide powders with aluminum oxide Рис. 11. Электронно-микроскопические изображения наноструктурированного твердого сплава, EDS-карта локального залегания легирующего компонента на поверхности твёрдосплавного композита, изготовлен- ного на основе микронных порошков карбидов с добавками оксида алюминия a b Fig. 12. X-ray structure analysis of hard-alloy composites consolidated by electro-impulse plasma sintering method using nanoparticle additives: a - 1 %; b - 3 % Рис. 12. Результаты рентгеноструктурного анализа твердосплавных композитов, консолидированных методом ЭИПС с количеством добавок наночастиц: а - 1 %; б - 3 % Some strength characteristics of hard-alloy composites Composition of the material Physicomechanical characteristics Hardness HV, ГПа Tensile strength at bending Rbm, ГПа Crack resistance КIс, МПа × м1/2 Microcrystalline, ВК15 + Al2O3 12.7 2.54 21.6 Microcrystalline, BK10KC + Al2O3 15.1 2.68 19.3 Quasy- nanocrystalline ВК6 19.5 ± 0.6 2.03 ± 0.1 9.1 ± 0.6 ВК6 + 2 % ZrO2 20.4 ± 0.6 2.17 ± 0.1 9.3± 0.7 ВК6 + 4 % ZrO2 22.0 ± 0.6 2.09 ± 0.1 9.7 Conclusion. The conducted complex parametrical re- search results demonstrate that when modifying hardalloy composites by nanoparticles the principle of “com- position-structure-property”, known in materials science, is implemented. In total, the received results of experi- mental studies in combination with methods of computer modeling and prediction of hard-alloy composites proper- ties, modified by additives of ceramics nanoparticles, provide expansion of opportunities for structure and hard alloys properties operation. Composite submicronic powders (WC-Co) use in combination with modifying nanoparticles Al2O3, ZrO2 (inhibitors) is an efficient starting method of nanostruc- tured hard-alloy composites quality improvement. The calculated results (on the model) and the experimental studies comparison show satisfactory coincidence of the predicted microstructure parameters and strength proper- ties with the obtained.

Авторлар туралы

Yu. Gordeev

Siberian Federal University

79/10, Svobodny Av., Krasnoyarsk, 660041, Russian Federation

V. Jasinski

Siberian Federal University

79/10, Svobodny Av., Krasnoyarsk, 660041, Russian Federation

N. Anistratenko

Siberian Federal University

79/10, Svobodny Av., Krasnoyarsk, 660041, Russian Federation

A. Binchurov

Siberian Federal University

79/10, Svobodny Av., Krasnoyarsk, 660041, Russian Federation

V. Vadimov

Siberian Federal University; JSC “Academician M. F. Reshetnev” Information Satellite Systems”

Email: vladimir-vadimov@mail.ru
79/10, Svobodny Av., Krasnoyarsk, 660041, Russian Federation 52, Lenin Str., Zheleznogorsk, Krasnoyarsk region, 662972, Russian Federation

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