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Composite materials on base of copper and molybdenum, condensed from vapor phase, for electric contacts. Structure, properties, technology: Part 2. Fundamentals of electron beam technology for producing materials for electric contacts.

In [1] scientific, technical, and economic premises are stated for producing materials for electric contacts by the method of high-rate EB evaporation of metals and subsequent condensation of vapor flow in vacuum on a preliminary heated substrate.

In this article results of development of EB technology fundamentals for production of composite materials (CM) for electric contacts, which don't contain noble materials, and investigation of their structure and properties are presented.

Technological peculiarities of manufacturing condensed CM. For producing electric contact materials, condensed from vapor phase, commercial EB installation UE-189, designed in the E.O. Paton Elec tric Welding Institute and modified in SIE <<Gekont>>, was used. Appearance of the installation is shown in Figure 1. Its principle scheme is shown in Figure 2. The installation has a working chamber 1, which is at the same time a technological chamber. To the side part of this chamber gun chamber 2 is joined, in which EB heaters 3--6 are located.

[FIGURE 1 OMITTED]

[FIGURE 2 OMITTED]

The vacuum system is designed for creating dynamic vacuum in chambers of the UE-189 installation for the purpose of ensuring process of evaporation and condensation of initial materials. The technological chamber and the gun chamber have separate vacuum pump-out systems, which ensure stability of EB heater operation.

The vacuum system consists of two roughing-down pumps AVZ-125, two booster pumps NVBM-05, and two high-vacuum units AVP-400 (one per the gun chamber and the technological chamber). Design of the vacuum system ensures emergency shut-off of pipelines by vacuum valves KMU-63 in case of a sudden de-energizing.

On upper flange of the technological chamber 1 substrate 14 rotation mechanism 15, designed and manufactured in <<Gekont>>, is installed [2]. Peculiar feature of the design of this mechanism is possibility of its long operation (10--12 months) without violation of vacuum when rotating a substrate of up to 50 kg mass at speed up to 40 rpm at the temperature (600 [+ or -] 50) [degrees]C.

Heating of the substrate (fixed on the rotation rod 7) up to the mentioned temperature [3] is performed by EB heaters PE-112 5, 6 of 40 kW power. Heating of the initial material for evaporation is performed by means of EB heaters PE-104 3, 4 of 100 kW power. All heaters have independent filament of cathodes and control of EBs. Service life of cathodes of the PE-112 guns achieves 50 h, PE-104 guns--30 h.

Evaporation unit consists of two crucibles of 100 and 70 [micro]m in diameter (8 and 9, respectively), designed for evaporation of copper 10 and molybdenum 11, and mechanisms 12 and 13, which ensure their feeding into the evaporation zone.

Initial (being evaporated) materials. For producing condensed electric contact materials copper, molybdenum, and alloying elements (yttrium and zirconium) were used as initial elements. Calcium fluoride was used for creation of a separating layer on the substrate. Chemical composition of mentioned materials corresponded to the requirements established for copper of grades M0-M3 in GOST 859--78; pure molybdenum of vacuum remelting (PMVR) in TU 4819-247--87; zirconium in TU 5-20-069--85; yttrium ITM1, ITM2 in TU 48-4-208--72; fluoric calcium of grade Ch in GOST 7167--77.

For production of copper ingots it was allowed to use the waste (condensate deposited on the chamber walls) and initial copper at the ratio 50:50.

Substrates for deposition of 800--1000 [micro]m in diameter and (20 [+ or -] 2) [micro]m thick were manufactured from steel St3. Surface of the substrate, on which deposition was performed, was subjected to milling and grinding till roughness not less than [R.sub.a] = 0.63 (GOST 2769--73) was achieved.

Preparation of ingots for evaporation. Copper ingots were turned and drilled for placement of alloying element weights. These ingots and turned ingots of molybdenum were subjected to cleaning, de greasing, and weighing. Alloying elements were used in the form of degreased and dried chips of zirconium and yttrium. Weights of mentioned metals at the ratio 7:3 in amount (100 [+ or -] 3) g per 10 kg of copper were placed into special channels, drilled in copper ingot being evaporated, and on surface of the latter. For creation of a separating layer a weight of fluoric calcium (2.0 [+ or -] 0.3 g) was placed on the surface being heated of the molybdenum ingot.

After charging of the substrate and initial materials to be evaporated the installation was vacuumized. After vacuum 1-[10.sup.-2] Pa was achieved, EB heaters were switched on and technological process of vacuum deposition was started.

Deposition of the separating layer Ca[F.sub.2] was performed in vacuum not less than 1 * [10.sup.2] Pa after heating of the rotating substrate up to the temperature (873 [+ or -] 50) K. Duration of the separating layer application was 120--180 s.

After termination of the separating layer deposition process, alloyed pool was formed on the copper ingot face. At the same time molybdenum ingot was heated. The conditions were considered achieved when evaporation currents of copper equaled 3.0-3.4 A, molybdenum--1.2--16 A at acceleration voltage of 20 kV. Change of the beam power in evaporation of molybdenum in different experiments allowed producing electric contact CM Cu--Mo--Zr--Y of three grades (MDK-1, MDK-2, MDK-3) with molybdenum concentration equal to 2.5--5.0, 5.1--8.0, 8.0-12.0 wt.%, respectively [4].

In [1] experimental data and existing ideas concerning selection of base and alloying elements for development of CM of electric contact designation, which don't contain silver, are presented. One of the main issues in development of EB technology, which requires for solution, is the issue of increasing intensity of the metal evaporation process.

Evaporator, rate of evaporation, composition, structure. When selecting methods of copper evaporation intensity change, we proceeded, first of all, from the known data on existing methods of such regulation. Most frequently rate of evaporation is increased by increasing size of the evaporator and power of EB [5-7]. However, when 50 kW power and specific rate of copper evaporation from the water-cooled crucible 4-[10.sup.3] g/([cm.sup.2]-s) is exceeded, stability of the pool is violated: splattering of metal from the crucible takes place. Outburst of the metal may be partially avoided by introduction of alloying additives and arrangement of a multi-component pool on surface of the melt being evaporated (an intermediate pool) [8, 9].

In [10] the intermediate pool is called melt of the additive-metal, which restrictedly interacts with the base metal, occupies [approximately or equal to] 10 % of the whole melt volume, and preserves on its surface. The main requirement to the additive-metal is lower density than in the metal-base, and pressure of its vapors within technological range of temperatures should be lower than that of the metal-base. From chosen by us alloying elements [1], zirconium completely and yttrium partially met these requirements. Density values of zirconium--6.49-[10.sup.3] and yttrium--4.55-[10.sup.3] are lower than those of copper--8.92-[10.sup.3] kg/[m.sup.3]. As far as pressure of vapors is concerned, for copper and zirconium required difference is preserved, while for copper and yttrium it is not so significant (Figure 3) [11]. However, according to [10], zirconium and yttrium increase specific rate of copper evaporation. From analysis of Figure 4, presented in [10], one can see that alloying elements in copper melt accelerate evaporation of copper: zirconium--2 times, vanadium--almost 6 times. There is no satisfactory explanation of evaporation rate increase in case of using an intermediate pool. It is assumed that increase of evaporation rate may be caused by surface tension and heat conductivity of the melt being evaporated, which change during alloying [12]. However, peculiarities of phase equilibriums in binary systems Cu-Zr, Cu--Y, Cu--Nb, Cu--Fe and Cu--V may influence specific rate of the melt evaporation.

[FIGURE 3 OMITTED]

Four intermetallic compounds (Y[Cu.sub.6], Y[Cu.sub.4], Y[Cu.sub.2], YCu) were detected in binary system Cu--Y, three of which melt congruently within temperature range of (935 [+ or -] 15)--(985 [+ or -] 15) [degrees]C. In the system Cu-Y also four eutectic transformations were registered, which proceeded within temperature range (890 [+ or -] 10)--(760 [+ or -] 15) [degrees]C and yttrium concentrations 12.5-74 wt.% [13].

[FIGURE 4 OMITTED]

There are six intermettalic compounds in binary system Cu--Zr, four of which melt congruently. All compounds participate in eutectic reactions within concentration range of zirconium content 8.85-55 wt.% and temperature range 971--885 [degrees]C [13].

So, during interaction of elements in each mentioned binary system exists within wide range of concentrations probability of formation of eutectic type melts with significantly lower melting point than that of initial metals.

For binary systems Cu--V, Cu--Nb and Cu--Fe presence of areas of immiscibility and lamination (with the maximum, approximately, in equimolar area) is characteristic, and monotectic reaction, for example, in system Cu--V at temperature 1530 [degrees]C, and in system Cu--Nb at temperature 1550 [degrees]C [13]. This allows assuming possibility of morphology change of structural components of the system and properties of its capillarity and increase of evaporation rate at the temperature, which significantly exceeds copper melting temperature, which does not contradict data of [10] that prove increase of copper melt evaporation rate in presence of vanadium, niobium and iron additives.

In the process of development of technology for manufacturing massive Cu--Mo--Zr--Y condensed materials samples of three alloyed pools were investigated, which ensured three rates of condensation that made up 16--20, 8--10, 4--5 [micro]m/min, respectively. For investigation of pool materials optic and electron scanning microscopy, X-ray spectral microanalysis, and method of microhardness were used. Despite different values of density of alloying elements of yttrium and base metal (copper), lamination of components in the pool was not detected.

Active interaction of these elements with copper, each other, and interstitial impurities was noted. Phase composition of the pools after solidification corresponded mainly to twin diagram Cu--Zr, according to which in equilibrium with copper-base solid solution exists intermetallide Zr[Cu.sub.5], which forms due to peritectic reaction, and intermetallide Zr[Cu.sub.4], which represents a congruently melting compound. Different mass shares of zirconium in these phases (in Zr[Cu.sub.5] approximately 22 %, in Zr[Cu.sub.4]--26 %) and morphology of the latter (Figure 5) allow assuming that crystals of intermetallide Zr[Cu.sub.4] of various shape form during solidification of the pool. Intermetallide Zr[Cu.sub.5] in the form of thin fibers precipitates in solid solution at the temperature below solidus, i.e. as a result of aging. In solidified pool 1, which ensures maximum rate of copper evaporation, big anisotropic particles prevailed (Figure 6, a) with sizes sometimes equal to the pool depth (approximately 12 [micro]m). It proves the fact that alloyed melt occupies the whole volume of the pool. In pool 2, where average rate of copper evaporation was 8--10 [micro]m/min, mainly anisotropic particles of intermetallide Zr[Cu.sub.4] were registered having a shape of somewhat elongated hexahedron (Figure 6, b). In pool 3, for which minimum rate of copper evaporation is characteristic (4- 5 [micro]m/min), size of isotropic particles in dominant areas sharply reduced (Figure 7, a). Structure of the pool was inhomogeneous. Near surface of the pool accumulation of anisotropic particles Zr[Cu.sub.4] was detected, as well as porosity (Figure 7, b) and slag inclusions in system Zr--Y--O (Figure 7, c). Disperse (anisotropic or isotropic) phase Zr[Cu.sub.5] (Figure 5) was present in investigated pools between particles of intermetallide Zr[Cu.sub.4]. In the near-bottom zone this very phase formed branched structure (Figure 8).

So, it was experimentally established that content and distribution of elements in the alloy Cu--Zr--Y with high rate of evaporation during solidification ensure formation of anisotropic structure, which is stipulated by directed growth of intermetallide Zr[Cu.sub.5]. Absence of sufficient knowledge about mechanism of melting and solidification does not allow authentic judging of the nature of detected interrelation. However, data of [14, 15] prove that the melt has to be considered as a crystal dispersed into clusters of 0.5--3.0 nm size. That's why one may assume existence of hereditary connection between structures of copper-base alloys in liquid and solid state and influence of ordering on the melt evaporation rate.

On the basis of established peculiarities of the structure, phase, and chemical compositions of the pools one may draw conclusion that phase equilibriums in copper-, zirconium- and yttrium-base systems, complicated by presence of impurities in commercially clean materials, have to be considered as some of the main factors which control rate of evaporation-condensation.

[FIGURE 5 OMITTED]

Efficiency of alloying elements is, probably, stipulated by their ability to change structure of the melt and its capillary properties. This assumption fits established in [10] two-fold increase of the copper-base melt evaporation rate in presence of zirconium and yttrium, which form intermetallic compounds and low-melting eutectics in correspondence with similar equilibrium diagrams.

Evidently the same analogy of equilibrium diagrams in systems Cu--Fe and Cu--V (presence of areas of immiscibility in liquid state and possibility of monotectic reaction proceeding at reduced tempera ture of the ingot, which determine structure of the melt) allows achieving even higher (4--6-fold) increase of evaporation rate in the presence of additives of iron and vanadium.

[FIGURE 6 OMITTED]

[FIGURE 7 OMITTED]

[FIGURE 8 OMITTED]

Condensate, its composition, structure and properties. Ratio of values of pressure of metal vapors at various temperatures, composition and structure of the pool melt determine peculiarities of the condensate mass transfer and chemical composition. As follows from presented data and results of mass-spectral analysis of copper condensate, containing alloying elements zirconium and yttrium used during its production, zirconium is mainly accumulated in the melt, while yttrium participates more actively in mass transfer. According to the results of this analysis, weight share of alloying elements varies in zirconium within 0.01--0.08 and in yttrium within 0.02--0.012 %.

The parameter, which allows qualitative estimating possibility of increasing intensity of the alloying element mass transfer, may be the temperature, at which pressure of saturated vapor 133.3 Pa is achieved [16]. For example, for iron, yttrium and zirconium it increases at 1923, 2128, and 2883 K. In the same sequence reduces content of elements in condensates Cu--Fe, Cu--Y, Cu--Zr (6.08--9.43; 0.13--0.18; 0.02-0.08 wt.%, respectively) [10]. These data don't contradict peculiarities of temperature dependence of vapor pressure of iron, yttrium, and zirconium (see Figure 3) [11].

When alloying elements get from the melt being evaporated into condensate, they notably affect its mechanical properties (Table 1) [10]. Morphology of an additive and its content affect properties of the initial condensate and intensity of its loss of strength at the temperature 573 K. Maximum worsening of properties was registered when copper condensate was alloyed with iron. Tensile strength of the condensate reduces by 63 % and relative elongation [delta]--by 24 %. The lowest reduction of property parameters--by 40 and 11 %--takes place, when the condensate is alloyed by zirconium, whereby it should be noted that tensile strength and ductility of pure copper reduce at 573 K by 48 and 47 %, respectively, in comparison with room temperature.

Taking into account structural sensitivity of mechanical properties, one may assume that strength reduction is stipulated by the processes of recovery and ability of alloying elements to hinder these processes by means of action on phase composition, morphology, and dispersibility of new phases. However, mechanical properties are affected, in addition to mentioned factors, by other factors as well. They are stipulated by application in technological processes of commercially pure initial materials and residual mediums.

In this work influence of impurities on structure and properties was investigated on samples of CM Cu--Mo--Zr--Y proceeding from the need of increasing the level, reproducibility of the condensate properties, and optimization of technological conditions of their manufacturing. Samples of copper- and molybdenumbase materials of grades MDK-1 and MDK-3 of various lots corresponding to TU U 201134.001--98 and containing up to 12 wt.% Mo and not more than 0.08 wt.% Zr and Y (each), the rest being copper, were used as objects of investigation [4]. Samples were cut out from condensate sheets of 800 [micro]m diameter. Size of samples allowed sequential performing macrostructural analysis of the surface, measuring thickness, density, electric resistance, hardness, and determining tensile mechanical properties.

Surface and sections of the samples parallel and perpendicular to the vapor flow (before and after etching), and fractures were subjected to microstructural investigations [17]. Thickness measurement of the samples showed that condensate, formed during rotation of the substrate, may be represented in the form of a truncated toroid. Cuneiform shape is characteristic of the periphery. Here thickness, in comparison with maximum for the toroid, reduces by (45 [+ or -] 3) %.

[FIGURE 9 OMITTED]

Surface of the samples is of block character (Figure 9). For each block periodic or arbitrary striation is characteristic. Investigation of condensates of different lots allowed establishing that in case of periodic striation width of strips and dispersion may differ by more than one order--from (35 [+ or -] 3) to (564 [+ or -] 32) [micro]m. One of the reasons of occurrence of such macro- and microstructure (striation) may be, evidently, peculiarity of the substrate roughness caused in the course of processing by a number of factors [18] (single- or multi-tooth milling, rectilinear or circular forming edge, error in location of the forming edge, error in the shape of the calibration edge, static rigidity of the technological system, in case of reduction of which self-excited oscillation develops in this system accompanied by abrupt increase of roughness and undulation) [10].

For the whole surface presence of solidified drops of thrown out from the metal pool and pimples is characteristic. Number of the latter ones varies depending upon the lot and may achieve 1-[10.sup.2] per 1 [cm.sup.2]. Formation of pimples is connected with throwing out and transfer on the substrate of liquid and solid phase drops at different stages of the evaporation-condensation process.

In Figure 10 surface with periodic striation and technological defects (micro-drops) is shown.

In perpendicular to the surface condensate section laminar structure was detected, which had macrolayers of different thickness (0.1--1.5 [micro]m) with wide <<interfaces>> (Figure 11). Probably such interfaces correspond to a microlayer, which forms in case of a sudden cutout of high voltage, cessation of vapor flow delivery, adsorption of impurities from the residual atmosphere and oil vapors in working chamber of the installation. This assumption is confirmed by results of Auger-spectral analysis of boundaries of macrolayers brought out into the area of incision during preparation of the samples and destroyed in the microscope column. For this type of boundaries presence on their surface of carbon in graphite and carbide form, molybdenum, sulfur, chlorine, nitrogen, zinc, tin, etc. is characteristic [17].

Microstructural analysis of the condensate section perpendicular to the surface (after etching) proves inhomogeneous character of macrolayers and inhomogeneity of their structure, whereby in the section, perpendicular to the surface and the strips, mentioned layers are, like strips on the surface, of undulated character, inherited from roughness of the substrate. In section perpendicular to the surface, but parallel to the strips, undulated character of structure was not registered (Figure 12). Ion etching of section, perpendicular to the surface, allowed establishing that disperse-strengthened contact copper (MDK) consists, as a gradient material, from microlayers of different composition and morphology (Figure 13).

For the layers, enriched with molybdenum, anisotropic (columnar) structure is characteristic (Figure 13, a), which, according to [19], forms as a result of connection of atoms from a volumetric diffusion field (VDF) of the condensed flow with 2D insular layers by diffusion coalescence. Different thickness of the layers occurs in this case as a result of formation of more efficient VDF and increase of rate and time of condensation of the fed vapors.

For layers enriched with copper mainly isotropic structure is characteristic, which consists either of disoriented polygonal grains (Figure 13, b), or from particles of spherical and (or) lenticular form dispersed in the matrix (Figures 13, c and 14, a).

[FIGURE 10 OMITTED]

[FIGURE 11 OMITTED]

[FIGURE 12 OMITTED]

Such analysis of sections of these condensate samples allows assuming that correct spherical shape of particles and respective morphology of layers are connected with aggregated transformation in copper in the direction vapor [right arrow] liquid phase. Lenticular shape of particles forms, evidently, as a result of coalescence of solid-liquid clusters of CM Cu--Mo and origination of spherical particles during their approach to the substrate and deformation of these particles during their collision with the substrate and under action of the next portions of the <<drop>> vapor. This is proved by the shape of particles in Figure 14, a and b.

Turbulence of vapor flow may be the reason of formation of different forms of conglomerates during consolidation of particles in microlayers (Figure 14, c). Chemical etching of the section perpendicular to the condensate surface proves that in case of lower content of molybdenum in MDK-1, refractory component forms separated grains with d << 1 [micro]m and conglomerates of these grains in the copper-base matrix (Figure 15). When content of molybdenum in MDK-3 increases, chains of grains and anisotropic colonies form in the matrix.

[FIGURE 13 OMITTED]

Change of structure and chemical composition of microlayers fits peculiarities of the microhardness change. Microhardness increases together with increase of the share of columnar structure and molybdenum content in the layers.

In the process of mechanical tensile tests of condensed CM dependence of sample properties upon molybdenum content was also detected (Table 2). In case of annealing of the samples (1173 K, 3 h, vacuum), their strength reduces, ductility increases, but mean value of dispersion does not reduce. Ductility of samples, which correspond to periphery of the sheet, reduces because of lamination first of all along boundaries of macrolayers enriched with carbon and other impurities.

[FIGURE 14 OMITTED]

[FIGURE 15 OMITTED]

An important part in formation of structure and properties of condensates play defects, which formed as a result of outburst from molten pool and transfer of liquid and solid phases. Such outbursts of the melt differ from each other by composition, adhesion to previous layer of the condensate, ability to spread over it, shape, gas content, etc. For example, spheroids, which form during solidification of metal micro-drops, contain in addition to the base elements (molybdenum, yttrium, zirconium) carbon, oxygen, nitrogen, and fluorine. The most frequent forms of solidified drops are spheroid and spherical ones. Spheroids, being retained by the previous layer, cause distortion of subsequent solidification front. Convexity, which forms on these spheroids, is transferred to each subsequent layer up to the condensate surface and forms pimples on it (Figure 16, a), whereby in the condensate volume formations of cylindrical or conical form were detected, which were conditionally called <<rods>>.

Formation of <<rod>> boundaries, registered on microsections and fractures (Figure 16), is, evidently, connected with precipitation and redistribution of impurities during solidification of micro-drops, thrown away from the molten pool. As far as outburst and transfer of liquid and solid phases occurs during the whole process of evaporation-condensation, the <<rods>> either penetrate through the whole condensate thickness or only part thereof. Results of analysis of peculiarities of the condensate destruction in mechanical tensile tests showed that presence of the <<rods>> is characteristic of, approximately, 95 % of fractures. As far as interfaces of the <<rods>> with the condensate base metal are the places of plastic strain localization and formation of cracks, we compared mechanical properties of condensed CM with size and number of the <<rods>> registered on surface of a fracture.

It was established that presence of the <<rods>> in a fracture is accompanied by reduction of strength and ductility, degree of which depends upon significance of length, diameter and number of the <<rods>> in a section. If formation of a <<rod>> is stipulated by outburst of liquid phase at the final stage of condensation, reduction of ductility is not detected (Table 3) [17].

Failure of a sample may occur as a result of origination and development of a crack and near the notch on the surface, along boundaries of macro- and microlayers, <<rods>>, elements of columnar structure or other defects (Figure 17). However, significant improvement of the condensate properties was registered only when a fracture did not contain <<rods>> and in micro-volumes of the fracture increased part of fracture toughness due to formation and coalescence of pores (in presence of micro-particles of the refractory phase). Such character of failure was detected in MDK samples after annealing and at increased temperature of tests.

[FIGURE 16 OMITTED]

[FIGURE 17 OMITTED]

So, in condensed CM in system Cu--Mo--Zr--Y form, in addition to structural-dimensional hierarchy of main components, hierarchy of defects of this structure, provided commercially clean initial materials and residual medium are used. With hierarchy of defects localization of plastic strain in tensile tests and origination and development of cracks are connected.

Temperature dependence of mechanical properties of condensed CM of grade MDK-3 was studied (tests were performed in the Institute for Problems of Strength of the NAS of Ukraine by V.V. Bukhanovsky and N.P. Rudnitsky). Processing of the test results according to methodology of [20], which was carried out by us with determination of gross errors (blunders) in small samplings, allowed establishing stepwise character of strain activation energy change (Figure 18). Comparative analysis of these data and peculiarities of fracture of samples of two lots allow assuming that strain activation energy is minimal and makes up 0.061--0.062 eV within temperature range 300--500 K and corresponds to strain localization near the notches on the surface. Maximum strain activation energy 1.467--1.462 eV within temperature range 900-1100 K for the same lots is connected with fracture toughness of the material with isotropic and columnar structure (Figure 19). Within temperature range 500-900 K, evidently, takes place joint influence of weakened by impurities interfaces (macro-, micro-layers, columns in them, condensate, <<rods>>, etc.) on processes of deformation and failure.

[FIGURE 18 OMITTED]

[FIGURE 19 OMITTED]

The results obtained don't contradict assumption made in [20] about change of strain mechanisms (dislocation slippage for dislocation creepage) during tensile tests of copper within the same temperature range. Data of fractographic studies expand our idea about peculiarities and role of structure defects of condensed CM as places of localization of plastic strain, origination and development of cracks, and failure.

CONCLUSIONS

1. Main technological factors (combination of conditions--preparation of a substrate, its rotation, alloying of the pool, conditions of the pool heating, etc.) which affect process of evaporation and structure formation of condensed composite materials are established.

2. It is shown that in case of copper alloying by the elements, which may affect rate of the melt evaporation, peculiarities of phase transformations in binary and more complex systems and possibility of morphology control of structural components and capillarity of a system in liquid-solid state have to be taken into account.

3. It is established that condensate surface at the condensation front is of block character with periodic and arbitrary striation according to roughness of the substrate. Behind condensation front lamellar structure with hierarchy of layers was detected, which had columnar, polygonal disoriented, composite (with spherical, lenticular or mixed shape) structure, varieties of which corresponded to the condensation mechanisms.

4. It is determined that peculiarities of formation of technological defects are connected with outburst of the pool material in solid and liquid phases and segregation of impurities on interfaces of structural components.

5. It is shown that in tensile tests of copper- and molybdenum-base condensates, which contained defects of structure, reduction and instability of mechanical properties were registered stipulated by combined or separate influence of defects on peculiarities of deformation and failure. In case of the tensile test temperature increase and change of the nature of structure defects, which determine localization of plastic strain, origination, development of cracks and failure match well stepwise change of strain activation energy.

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[2.] Grechanyuk, M.I., Osokin, V.O., Afanasiev, I.B. et al. Composite material for electric contacts and method of its producing. Pat. 34875 Ukraine. Int. Cl. C23C/20. Publ. 30.12.2002.

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[10.] Movchan, B.A., Osokin, V.A., Pushechnikova, L.V. et al. (1991) Electron beam evaporation and condensation of copper through intermediate pool. Problemy Spets. Elektrometallurgii, 3, 58--61.

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[17.] Minakova, R.V., Osokin, V.O., Grechanyuk, M.I. et al. (2001) About structure aspects of formation and fracture of condensed composite copper-base materials. In: Transact. of IPM NANU on Electron Microscopy and Strength of Materials. Kiev.

[18.] (1991) Science and technological advance. Technological peculiarities of tool machining of polycristalline superhard materials. Ed. by G.R. Korzh. Kiev: Naukova Dumka.

[19.] Pereplyotov, V.I., Kosminskaya, D.A., Kravchenko, S.A. (2003) Principles of structure formation on low-supersaturated vapor condensates of Cu, Ti, Al and Cr. In: Transact. of IMF NANU, 25(6), 725 -735.

[20.] Krashchenko, V.P., Stetsenko, V.E. (1981) Influence of temperature and deformation rate on main processes controlling the copper strength. Problemy Prochnosti, 4, 78 -83.

N.I. GRECHANYUK, V.A. OSOKIN, I.N. GRECHANYUK, P.P. KUCHERENKO, R.V. MINAKOVA,

M.E. GOLOVKOVA and G.E. KOPYLOVA

Scientific-Industrial Enterprise <<Gekont>>, Vinnitsa, Ukraine
Table 1. Influence of alloying elements on mechanical properties
of copper-base condensate

Material Mechanical properties of condensates T, [degrees]C

 20 300

 [[delta].sub.t], [delta], [[delta].sub.t], [delta],
 MPa % MPa %

Cu 188 62 98 33
Cu-Y 213 53 79 34
Cu-Zr 192 56 115 50
Cu-Fe 318 33 118 25

Table 2. Influence of annealing on mechanical properties of
condensates MDK-1 and MDK-3

Alloy Initial state of CM
grade

 [[delta].sub.t], MPa [delta], %

MDK-1 518 [+ or -] 118 0.69 [+ or -]0.53
MDK-3 659 [+ or -] 106 0

Alloy Annealing of CM at 900 [degrees]C
grade for 3 h

 [[delta].sub.t], MPa [delta], %

MDK-1 543.0 [+ or -] 60.9 2.4 [+ or -] 1.1
MDK-3 629.3 [+ or -] 61.3 0.79 [+ or -] 0.57

Table 3. Influence of size of <<rods>> on mechanical properties of
condensate MDK-1

Sample Size of defects, mm Mechanical properties
No.

 d l [[sigma].sub.t], MPa [delta], %

17 0.415 1.00 602 N/D
24 0.46 0.63 628 0.95
 0.32 0.53
18' 0.54 1.06 575 N/D
20' 0.25 1.14 634 0.3
 0.25 1.15
22' N/D 666 2.6
30' Same 686 2.1
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Title Annotation:ELECTRONIC BEAM PROCESSES
Author:Grechanyuk, N.I.; Osokin, V.A.; Grechanyuk, P.P.; Kucherenko, R.V.; Golovkova, M.E.; Kopylova, G.E.
Publication:Advances in Electrometallurgy
Article Type:Report
Date:Apr 1, 2006
Words:5386
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