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Session Chairperson: Dr. John A. Shields Jr., Climax Specialty Metals, 21801 Tungsten Road, Cleveland, OH 44117; Dr. Omar Es-Said, Loyola Marymount University, Los Angeles, CA 90045-2699
STRUCTURES AND PROPERTIES OF Mo-Re ALLOYS: Fumio Morito, National Research Institute for Metals, 1-2-1 Sengen, Tsukuba 305, Japan
It is well known that MO-Re alloys exhibit superior properties among Mo based alloys. However Re effect on the structures and properties of Mo has not well understood. The current state of Mo-Re alloys was therefore reviewed not only in the field of high temperatures but also in the application of high performance. Focusing on the effect of Re concentrations in Mo, the structures and properties of the welds produced by electron beam welding were investigated. Bend and tensile behaviors of the welds were evaluated. Microstructures and fracture surfaces of the welds were examined in details by SEM/EDX and TEM. Furthermore formation and distribution of sigma-phase in Mo-Re welds were studied. A role of signa-phase on the structures and properties of Mo-Re alloys was also discussed.
THE ORIGIN OF THE INHOMOGENEOUS RHENIUM DISTRIBUTION IN POTASSIUM DOPED W-Re ALLOYS: I. Gaal, Research Institute for Technical Physics of the Hungarian Academy of Sciences, H-1325, P.O. Box 76, Budapest, Hungary
MECHANICAL ALLOYING OF W-25wt.%Re POWDER: F.H. Froes, C.R. Clark, C. Suryanarayana, E.G. Baburaj, Institute for Materials and Advanced Processes, University of Idaho, Mines Building, Room 321, Moscow, Idaho 83844-3026; Boris D. Bryskin, Rhenium Alloys, Inc., P.O. Box 245, Elyria, OH 44036-0245
Mechanical alloying (MA) of well characterized elemental W (75 wt.%) and Re (25 wt.%) was carried out in a SPEX Mill at ambient temperature for 1,3,5 and 10 hours. Milled products were examined for structural, chemical and morphological details using x-ray diffraction, scanning electron microscopy and transmission electron microscopy. XRD patterns showed continuous decrease in the intensity of Re peaks, with increasing MA time. However the Re peaks continued to be present even after 5 hours of milling. Ten hours of milling showed complete dissolution of Re, as observed by the complete absence of Re peaks in association with W peak shift in accordance with the dissolution of Re in W. Extensive reduction in particle size and chemical homogeneity of the alloy could be established by microstructural and chemical analysis using SEM and TEM. After pressing and sintering of pellets, tests revealed a significant amount of contamination by iron through milling.
THE KEY POINT OF TUNGSTEN-RHENIUM ALLOYS PROCESSING: Ms. Song Lin, 62 Amethyst Way, Franklin Park, NJ 08823
Tungsten-Rhenium alloys have won an important application in various modern technical fields and achieved great economic- technical effects and primarily produced by powder metallurgy. Nevertheless, the practical uses of tungsten-rhenium alloys sometimes are limited due to some difficulties encountered in their processing and applications. The common troubles are as follows: 1). The inhomogeneity of the alloy's composition. 2). The bubbling effect, during sintering of alloy rods. 3). Breaks occurred in winding formation of the alloy wire. 4). The formation of brittle second phases in the alloy. With the purpose to improve the properties of Tungsten Rhenium alloys. A systematic investigation of above mentioned problems are summarized.
9:50 am BREAK
9:30 am BREAK
MECHANICAL BEHAVIOR OF DILUTE Mo-Re ALLOY: R.W. Buckman, Jr., Refractory Metals Technology, Pittsburgh, PA 15236
The creep-rupture life of unalloyed molybdenum at 0.65Tm is only increased by an order of magnitude with up to 50% Re addition. A proprietary process, developed for unalloyed molybdenum, results in an increase in creep-rupture life at 0.65Tm by 4-5 orders of magnitude. A Mo-14Re alloy processed by a similar method exhibits comparable creep rupture strength while recrystallized material retains a DBTT significantly below room temperature.
THE INFLUENCE OF RHENIUM ON STRUCTURE AND STRENGTH CHARACTERISTICS OF THE HIGH-TEMPERATURE STRENGTH EUTECTIC CHROMIUM BASED ALLOYS: L.V. Artyuh, O.A. Bilous, A.A. Bondar, M.P. Burka, S.A. Firstov, N.I. Tsyganenko, T. Ya. Velikanova, Frantsevich Institute for Problems of Materials Science, 3 Krjijanovskogo Str. 252680 Kiev, Ukraine
In our Institute some data were obtained that chromium-carbide eutectic cast alloys have prospects promising. The eutectic (CR)+(TiC) alloy has Vickers hardness about 100 Kg/mm2 at 1000°C and is harder than traditional commercial alloys on the base of iron, cobalt or nickel in some times about 1000°C. And what is more that the latter is able to be machined with the former at high temperature. Produced from (Cr)+(TiC) swages allowed to carry out isothermic swaging of high-temperature strength X220BX alloy (the Ni-based material for vane gas-turbine engine) in air at 1150°C and 200 Mpa stress. Molybdenum additions to the eutectic (Cr)+(TiC) alloy were determined to increase high temperature hardness to 1000°C up to 200-300 Kg/mm2. Continuing development the effect of rhenium on the structure and high-temperature hardness of eutectic two-phases (Cr)+(TiC) alloys in Cr-Ti-C and Cr-Mo-Ti-C systems was examined in this investigation. The rhenium additions being 5, 10 and 20 at. & were shown to lead to the formation of limited quantity of third phase, (Cr23C6). Highly dispersed eutectic structure became more homogeneous. According to microprobe analysis the rhenium (as molybdenum) is predominatly dissolved in chromium matrix. High-temperature hardness was determined to be increased already with 5 at.% Re additions. The develop is about 100 kg/mm2 at 300-800°C and about 40 Kg/mm2 at 1000°C. It became higher with increasing rhenium content up to 20 at.%. The hardness of five-component alloys was always more than four-component at the whole temperature interval. The maximum was found at maximum rhenium content (450 Kg/mm2 at 900°C). to our mind the develop was achieved due to solid solution strengthening of chromium matrix (well-known "rhenium effect"). The determined of hardness allows to estimate the strength characteristics using the =HV/3 connection. Therefore the eutectic (Cr)+(TiC) alloys with rhenium alloying are believed to become more perspective for application.
HIGH-RHENIUM BINARY AND TERNARY ALLOYS WITH TUNGSTEN AND MOLYBDENUM FOR SERVICE IN NITROGEN- AND HYDROGEN-CONTAINING ENVIRONMENTS: K.B. Povarova, N.K. Kasanskaia, O.A. Bannikh, I.D. Marchukova, V.L. Likov, Baikov Institute of Metallurgy, Russian Academy of Sciences, Leninskii Pr. 49, 117334 Moscow, Russia
Microstructure, fracture mode and mechanical properties of vacuum melted binary WR-27VM, MR-47VM alloys and ternary MWR-10/45VM alloy both deformed and recrystallized are investigated in the temperature range of 20-1200°C. Conditions for o-phase precipitation hardening are found. The effect of a-phase on the low-temperature ductility and low and high-temperature strength is estimated. Corrosion resistance at 400-1000°C and features of the chanses in surface layer composition in products of ammonia thermal dissotiation are investigated. It is shown that ternary alloy has high low-temperature ductility and strength and moderate high temperature strength as these of MR-47VM as well, as high corrosion resistance in ammonia dissotiation products close to that of WR-27VM. Mechanisms of surface layer composition changes in corrosion atmosphere are discussed.
THE SYNTHESIS OF W-Re POWDER ALLOYS: V.V. Panichkina, V.V. Skorokhod, Frantsevich Institute for Problems of Materials Science, 3 Krjijanovskogo Str. 252680 Kiev, Ukraine
The fine particle powder technology was used for the production of W-Re alloys. Single phase W-Re powders were obtained by co-reduction of fine particle W-Re oxide blends. The homogeneous disperse W-20%Re powders and the single phase W-80%Re intermetalide powder with particle size in range of 1- 4 µk were synthesized. W-20%Re powder was mixed with the W powder of the same dispersion in order to obtain W-2%Re alloy. The -phase would not be formed during the sintering because Re in blend is in form of the prealloyed W-20%Re powder. The synthesized W-2%Re ingots were rolled in 2-3 mm sheets. The mechanical characteristics and the structure of the material were investigated. The sheets had higher plasticity due to the 2%Re alloying. The W-80%Re alloy powders were successfully used for the production of long working time impregnated cathodes.
NEW METHODS OF IMPUTTING RHENIUM AND MANUFACTURE OF TUNGSTEN-AND MOLYBDENUM-RHENIUM ALLOYS: V.V. Khaydarov, P.S. Maksudov, V.I. Pack, A.A. Pirmatov, Uzbek Refractory and Heat Resistant Metals Integrated Plant, 702119 Chirchik, Tashkent Region, Republic of Uzbekistan
Uzbek Refractory and Heat Resistant Metals Integrated Plant is a complex enterprise infield of manufacture tungsten, molybdenum, rhenium, and alloys on their basis. There is a special technology of imputing rhenium from molybdenum concentrates, which contains from 300 GR. to 700 GR. rhenium per each 1 ton of concentrate at the enterprise. Moly concentrates are manufactured by method of nitrogen acid imputing. In this case basic point of rhenium transferring into liquids which contains molybdenum, rhenium and nitrogen and sulfur acids. Using such types of liquids, there are well known methods such as extraction and distilled rectification methods of imputing rhenium. And all above mention of methods have low effect. That is why researching in field of sorption technology of imputing rhenium from nitrogen-sulfur liquids. Researching of wide range of low, middle and high basis of anionites determined that the best one is vanil-peridium resin. Using such type of resin in industry we achieved 80% imputing rhenium as ammonium perrenatum. There is wide range of utility possibilities now we can use our own rhenium and produce powder alloys on basis of tungsten and molybdenum. Tungsten alloys are: BP-3; BP-S; BP-20. Molybdenum alloys are: MKP-16; MP-47. Wire produced from tungsten and molybdenum alloys using in thermometry and tube building industry as they have hardest characteristics.
11:30 am POSTER PRESENTATION
THE STRUCTURE AND PROPERTIES OF THE ALLOYS OF Re-Cr-C TERNARY SYSTEM: T. Ya. Velikanova, A.A. Bondar, A.V. Grytsiv, Frantsevich Institute for Problems of Materials Science, 3 Krjijanovskogo Str. 252680 Kiev, Ukraine
Existence of the rhenium effect improving the mechanical properties of the multycomponent chromium alloys (containing the rhenium and carbon together with other elements) specifies our interest in Re-Cr-C ternary system. Constitution and properties of more than 40 alloys prepared by arc melting were investigated by metallography, x-ray diffraction, microprobe and differential thermal analyses and Pirani-Altertum method in total concentration range. Rhenium raises the melting point of bcc chromium based phase (up to 2284°C in binary system Re-Cr). The maximum temperature of melting for the carbon and rhenium saturated chromium in equilibria with (Cr,Re)23C6 and (-Re3Cr2) amounts to 1650°C and appear more high then melting temperature for binary alloys containing Cr and Cr23C6 phases (1581°C). Ternary alloys of this two phase field have higher strength and ductility than binary ones. It is in according to data about existence rhenium effect in chromium based alloys. Essential singularity of Re-Cr-C system is immensely high combined solubility of the chromium and carbon in rhenium at high temperatures (about 50 at% Cr at 30 at% C: and 1710°C) and significant solubility of rhenium in chromium carbides (the most solubility Re in Cr23C6 amounts to 18, in Cr7C3 and Cr3C2 ones do 8 and 6 at.% at, 1655, 1710 and 1760°C, respectively ). Rhenium based solid solution forms equilibria with carbon, solid solutions of rhenium in chromium carbides and (-Re3Cr2) and thus it specifies the constitution of Re-Cr-C ternary system.
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