Interconnection between short-term strength, static stress-rupture strength, and creep resistance of tungsten, molybdenum, and alloys based on them

Comprehensive analysis of experimental data for the high-temperature mechanical properties of commercial purity tungsten, molybdenum, and their alloys with solid solution, dispersion, and mixed hardening prepared by powder metallurgy with different forms of uniaxial tension is provided. It was established that for materials of this class at high temperature (0.5–0.8 T_m) there is a close correlation between short-term and static stress-rupture strength, and creep resistance, which is described by unified functional dependences that are common for all of the metals and alloys studied. Institute of Strength Problems, Ukraine National Academy of Sciences, Kiev. Translated from Poroshkovaya Metallurgiya, Nos. 7–8(408), pp. 93–99, July–August, 1999.     

Phase transformations in uranium,plutonium, and neptunium

The actinide metals uranium and neptunium are characterized by three allotropes, and plutonium has six solid phases with two of the allotropes having complex, low symmetry, crystal structures. Further, many phase changes in these metals are accompanied by a large specific volume change and a large enthalpy change. Phase transformations in uranium and plutonium have been studied extensively but very little experimental work has been conducted to understand the phase transformations in neptunium. The low temperature transformations occur isothermally and exhibit simple TTT curves similar to many alloys. The kinetics in the metals are controlled more by purity and thermal history than by any inherent feature of the metals. Mechanisms in the pure metals are inadequately understood, and the crystal-lographic relations are complex. The β → α transformations in uranium and plutonium are diffusional near the α β equilibrium temperature, and they are both reminiscent of shear transformations at low temperatures. Skip transformations have been studied in these metals and the role of grain size on transformation behavior has been investigated more than in other metals. Accordingly, the roles of metal purity, thermal history, microstructure, mechanical properties, and thermodynamic variables are discussed, particularly as they might be related to phase transformations in other systems. Generalities have been difficult to establish for plutonium and uranium alloys. Among well-known metals the zirconium and titanium transformations form the closest analogs to the uranium transformations, but there is no obvious analog to the plutonium transformations. Formerly with the Argonne National Laboratory, Argonne, Ill. 60439, This paper is based on a presentation made at a symposium on “Phase Transformations in Less Common Metals: A Dialogue,” held at the Fall Meeting in Cleveland on October 16, 1972, under the sponsorship of the Phase Transformations Activity, Materials Science Division, American Society for Metals.     

Study of extraction and purification of Ni, Co and Mn from spent battery material

In spent battery material, there are plenty of valuable metals, such as copper, nickel, cobalt, manganese. Recovery of valuable metals from spent battery material not only protects the environment but also improves the utilization of resources and decreases the cost of battery material. In this study, hydrochloric acid is used as lixivant with characteristics of faster leaching rate and being recycled easily. The optimal conditions are that hydrochloric acid concentration is 6 mol/L, reaction temperature is exactly 60 °C, liquid/solid ratio is 8:1, (H₂O₂)_mol/(MeS)_mol = 2, and the leaching time is 2 h, the results show that the dissolution yields of Ni, Co and Mn can be 95 wt.% at least. The basic purification concept of the leaching solution includes that copper is removed through replacement by iron powder followed by iron precipitation in goethite method. The results show that Cu and Fe can be removed 99 wt.% at the least. At the same time, the loss of Ni, Co and Mn is not beyond 2 wt.%, 3 wt.％ and 2 wt.%, respectively. This method makes the preparation of pure Ni_xCo_yMn_z ternary system precursor economical. The process seems to be able to claim base metals from waste in a reliable and feasible way.     

Effect of electrode (tool) material density on the electric-spark alloying process

Conclusions Determinations were made of the effect of sintering temperature on density, hardness, and transverse rupture strength for VK6 and T30K4 hard metals. The relationship was found between the increase in volume of the layer forming on the cathode base plate and the starting porosity of a hard-metal alloying electrode. It is shown that a residual porosity of hard metals of 7–9% ensures optimum conditions of coating formation in the ESA of steel.Translated from Poroshkovaya Metallurgiya, No. 7(223), pp. 53–55, July, 1981.     

The compressibilities of liquid Sn-Tl,In-Bi,Sn-ln,Bi-Sb,and Bi-Cd-Tl alloys

The velocity of 5 mHz ultrasonic waves was measured from the liquidus temperature up to a maximum of 500∮ to 650° for a certain number of liquid metals and alloys. A semiempirical model of the metallic liquid state was developed to fit the numerical data by varying its six parameters. This model was based on widely admitted assumptions and on an additional hypothesis concerning the excess volume redistribution among the atoms of the liquid. The six calculated parameters were found to have a physical meaning and could be related to the crystalline molar volume at 0∮K, to the activation energy for self-diffusion, and to the geometrical characteristics of hard-sphere dense random packings, for the low-melting polyvalent metals and alloys.     

Cohesive energy, properties, and formation energy of transition metal alloys

The cohesive energy of transition metals and its contributions related to the s-and d-electrons are calculated. The correlation of interatomic bonding strength, molar volume, and compressibility of transition metals with cohesion energy and corresponding contributions to it is shown. It is demonstrated that the s-electrons play an important part in the cohesion of transition metals. The main contributions to the formation energy of disordered alloys of copper with transition metals are calculated using the tight-binding approach. The results obtained are in qualitative agreement with experimental data on the thermodynamic properties of Cu-3d-metal systems. __________ Translated from Poroshkovaya Metallurgiya, Vol. 47, No. 1–2 (459), pp. 37–54, 2008.     

Effect of cooling after welding on microstructure and mechanical properties of 12 Pct Cr steel weld metals

The microstructure of three 12 pct cr steel weld metals with different nickel and nitrogen contents was studied in as-welded condition and after postweld heat treatment with and without intercooling. Tensile strength and impact toughness of the weld metals were investigated in different postweld heat treatment conditions. In weld metals heat treated without intercooling, austenite decomposed by a eutectoid reaction that resulted in M₂₃C₆ aggregates around retained δ-ferrite. Two morphologies of M₂N and MN precipitates were found in a low-dislocation α-ferrite. It was concluded that these phases were also transformed from austenite. In weld metals heat treated with intercooling, M₂₃C₆ precipitates were smaller and more homogeneously distributed. Different MN precipitates were found in the tempered martensite. The fracture mode of the weld metals at room temperature was mainly transgranular cleavage with some fibrous fracture. Intercooling treatment improved Charpy impact toughness of the 12 pct Cr steel weld metals substantially. It was found that the important microstructural factors affecting the impact toughness of the weld metals which were heat treated without intercooling were the sizes of the α-ferrite grains, nonmetallic inclusions, and M₂₃C₆ aggregates. For the weld metals heat treated with intercooling, the factors which affect the toughness of the weld metals were the sizes of martensite packets and nonmetallic inclusions.     

镍和钴的共同加入对钼的活化烧结作用

研究用少量钴、镍和Co-Ni化学沉积的钼粉的烧结特性,比较了钼和Mo-Co、Mo-Ni-Co系的烧结特性,测算了其活化能,结果表明:镍、钴和Ni-Co的添加均改善了其烧结性能,镍比钴的效果好,而Mo-Ni-Co系的活化烧结效果最好。     

Surface Tension of Liquid Alkali,Alkaline, and Main Group Metals: Theoretical Treatment and Relationship Investigations

An improved theoretical method for calculating the surface tension of liquid metals is proposed. A recently derived equation that allows an accurate estimate of surface tension to be made for the large number of elements, based on statistical thermodynamics, is used for a means of calculating reliable values for the surface tension of pure liquid alkali, alkaline earth, and main group metals at the melting point, In order to increase the validity of the model, the surface tension of liquid lithium was calculated in the temperature range 454 K to 1300 K (181 °C to 1027 °C), where the calculated surface tension values follow a straight line behavior given by γ = 441 – 0.15 (T-Tm) (mJ m⁻²). The calculated surface excess entropy of liquid Li (–dγ/dT) was found to be 0.15 mJ m⁻² K⁻¹, which agrees well with the reported experimental value (0.147 mJ/m² K). Moreover, the relations of the calculated surface tension of alkali metals to atomic radius, heat of fusion, and specific heat capacity are described. The results are in excellent agreement with the existing experimental data.     

Temperature dependence of the strength of sintered TiB2-Fe composites

Conclusions A study was made of the effect of temperature in the range 20–1200°C on the transverse rupture strength of sintered TiB₂-Fe materials. It is shown that alloys of the TiB₂-Fe system surpass in high-temperature mechanical strength (>900°C) the standard hard metals.Translated from Poroshkovaya Metallurgiya, No. 7(235), pp. 94–97, July, 1982.     

Metals extraction with carboxylic acids. II. Effect of temperature on the extraction of Cu,Ni, Co(II), Zn,Fe(III) and Co(III)

The relation between the extraction temperature and the coefficient of distribution of various metals between aqueous phases and kerosene solutions of Versatic acid has been investigated.Using a mathematical procedure, it was established that with increasing temperature the distribution coefficient changes if the composition of the metal-Versatic complex is temperature-dependent. In the case of trivalent iron a reversible increase in distribution coefficient occurs when the temperature is raised. It is suggested that this is due to a reversible depolymerization of the complex. The distribution coefficient of trivalent cobalt also increases with temperature, but here the increase is irreversible, possibly because the number of covalently bound carboxylate groups changes.In general, the distribution coefficient of metals which do not show variations in the composition of their complexes with Versatic, such as Cu, Ni, Co(II) and Zn, does not change appreciably with temperature.     

A theory for solute impurity diffusion, which considers engel-brewer valences, balancing the fermi energy levels of solvent and solute, and differences in zero point energy

A theory that assumes the Engel-Brewer valence of elements (one for bcc structures, two for cph structures, and three for fcc structures) and considers the effects of balancing the solute and solvent Fermi energy levels and differences in zero point energy between solvent and solute atoms to calculate an “effective” relative valence for solute impurities is presented. The calculated values of relative valence and the experimental values of the differences in diffusional activation energy between solute and solvent atoms, ΔQ, are compared to the values of ΔH ₂ + ΔE calculated from the Lazarus-LeClaire theory for several solute impurities in ten solvent metals. The calculated results agree very well with the experimental values for the large majority of solutes. The theory presented adequately describes solute impurity diffusion in both α-Fe and γ-Fe, Al, Ni, and the noble metals. In particular, the low activation energies for impurity diffusion of the alkali metals (ground state valence of one) in Al (ground state valence of three) are accounted for by the theory. It is shown that the diffusion of the electronegative solute impurities (Cr, Mn, Fe, and Co) in Al is not anomalous when the relative valence is calculated by the proposed theory. The diffusion of electronegative solute impurities in the noble metals, which has been problematic in the past, is also well described by the proposed theory. The proposed theory introduces a simple method of estimating the effective electron densities of solute impurities and illustrates that the Lazarus-LeClaire theory adequately describes solute impurity diffusion in the ten solvent metals studied. It is expected that more accurate calculations of effective electron density for solute impurities would result in even better agreement between experimental and calculated results.     

难熔金属材料增材制造工艺研究进展

难熔金属材料具有良好的高温力学性能和高温稳定性,常用于制备耐热部件,被广泛应用于航空航天、国防工业等领域。然而,难熔金属的熔点比较高,室温塑性延展性能不佳,使用传统的加工方式制备复杂结构件时存在加工困难等问题。增材制造作为一项新兴的技术,基于三维模型数据,以激光、电子束、特殊波长光源、电弧及其多种组合作为能量源,利用“离散-堆积”成形原理制造实体部件,制备零件的尺寸可以从微米级到米级,为难熔金属复杂结构件的制备提供了新的途径。本文首先概述了增材制造技术的分类、特点及其应用,然后介绍了增材制造技术制备难熔金属的现状以及目前存在的主要问题,最后综述了增材制造工艺调控难熔金属材料微观组织和力学性能的研究进展,并对增材制造技术在难熔金属领域应用的发展方向进行了展望。     

高纯硫酸锰制备中除重金属新工艺的研究

研究了用MnS在高纯硫酸锰制备过程中除重金属的工艺方法,探讨了净化过程中反应温度、添加量及反应时间对除重金属的影响,并比较了用MnS、MnS矿、BaS除重金属的效果,得出高纯硫酸锰制备过程中用MnS除重金属能得到较理想的结果。     

Thermochemistry of alloys of transition metals: Part IV. Alloys of copper with scandium,yttrium, lanthanum,and lutetium

The enthalpies of mixing of liquid copper with liquid lanthanum, and with solid scandium, yttrium, and lutetium have been measured by high temperature reaction calorimetry at 1373 K. After correction for the enthalpies of fusion the limiting enthalpies of solution of the liquid metals in copper are-102 kJ mol^-1 (Sc), —105 kJ mol^-1 (Y), —103 kJ mol^-1 (La), and —120 kJ mol^-1 (Lu). We also report approximate enthalpies of solution of chromium and vanadium in copper; all values are compared with predictions published by Miedema and co-workers. The enthalpies of formation of eight congruent melting intermetallic compounds in the system Cu-Sc, Cu-Y, and Cu-La have been determined. The values are compared with corresponding data for the liquid alloys; this comparison provides approximate enthalpies and entropies of fusion for the intermetallic compounds. It is found that these entropies of fusion average 1. 1R to 1.2R,i.e., the values are comparable to those found for close-packed cubic metals. This indicates that the disordering of the two atoms probably contributes little to the entropies of fusion of the compounds.     

Conditions of preparation of borides of the platinum-group metals

Conclusions Thermal and x-ray phase analyses have been carried out to determine the conditions of reactive sintering of components resulting in the formation of borides of the platinum-group metals. It has been established that the reactive sintering temperature steadily falls as the d level of the platinum-group metals fills up.Translated from Poroshkovaya Metallurgiya, No. 8 (104), pp. 25–30, August, 1971.     

Relationship between some properties of the transition metals,characterizing their interatomic bond strength,and their electronic structure

Summary The change of some physical and thermodynamic properties of the transition metals is analyzed in relationship to their position in the periodic system of elements. On this basis it is shown that the increase of interatomic bond strength in each subgroup of the transition metals with increasing atomic number is largely due to the overlapping of the electron clouds of ions.It is necessary to distinguish two groups of physical properties of the transition metals, which characterize interatomic bond strength in the latter. The first group of properties characterizes the energy required for the full rupture of bonds in the crystal lattice and the second — bond deformability. The first group of properties includes the energy of sublimation and the melting point, and the second — the modulus of elasticity, the coefficient of compressibility, atomic diameters, and mean square displacements.The fact that bond deformability decreases in the crystal lattices of the first metals of group VIII compared with the metals of group VI and in the lattices of the copper-group metals compared with the titanium-group metals, although the energy required for bond rupture decreases, is attributed to increased overlapping of the electron clouds of ions.In metals, it is necessary to differentiate between the valence which characterizes the overlapping of the electron shells of ions (Pauling valence) and the valence due to collectivized electrons (Hume-Rothery valence).     

The effect of temperature on the hardness and modulus of elasticity of tungsten and molybdenum (20–2700‡)

Summary The results of an investigation of the temperature dependences of the harndess and Young's modulus of tungsten and molybdenum over a temperature range of 20–2700C are presented in the article.It was found that the temperature dependences of the ahrdness have two bends: a low-temperature bend at 0.14-0.2 and a high-temperature at a homologous temperature of 0.4–0.51. The temperature dependences of Young's modulus of these metals have only a single high-temperature bend at a homologous temperature of 0.5–0.55.The presence of bends is associated with the action of three basic mechanisms of plastic deformation at various homologous temperatures, as well as with a considerable change in the magnitude of the interatomic bonds at the high-temperature bend.     

Installation for vacuum-arc treatment of the surface of construction materials

A pilot installation for the vacuum-arc discharge treatment of the surface of metals and alloys for the preparation of the production process of the deposition protective coatings on articles made from construction materials is developed. Its design and working characteristics are presented. The prototype of an arc evaporator with an arc magnetic field functioning at nitrogen pressures in a working chamber of 10–1000 Pa, arc currents of 20–250 A, and voltages across a long arc up to 50 V is developed. It is shown that the properties of the surface layer of a steel sheet after its posttreatment storage under conditions of increased humidity for several years remained invariable.     

Composite magnetoabrasive TiC-Fe,VC-Fe,and Cr-C-Fe powders

Conclusions A study was made of the conditions of direct synthesis of composite MAMs from the simple substances. It has been established that the heating of mixtures of powdered carbide-forming transition metals (Ti, V, and Cr), carbon black, and iron in the temperature range 1300–2000°C results in preferential formation of titanium and vanadium carbides which are uniformly distributed in an iron matrix in the form of globules. The shape and size of the globules are determined by the carbide concentration in the composite and synthesis conditions. The chromium carbide Cr₃C₂ is not easy to synthesize in the presence of iron. The boundaries of fields of synthesized titanium and vanadium carbides in an iron matrix are clearly defined. The extent of carbide-iron interpenetration is negligible, not exceeding 3–7% of the carbide grain (globule) diameter. In the series Ti-V-Cr the degree of chemical reaction of these carbide-forming metals and their carbides with iron increases from titanium to vanadium and chromium. On the basis of data yielded by this investigation, a method is proposed for producing titanium carbide- and vanadium carbide-containing iron-base composite MAMs; the optimum compositions and conditions of synthesis of such composites have been determined. Pseudofused composite MAPs containing titanium and vanadium carbides possess excellent physicomechanical properties (grain strength, abrasive ability, and specific saturation magnetization intensity), and can be recommended for machining various materials, in particular steels. The results obtained have been utilized in the development of TU 6-09-4575-78 for MAMs, on the basis of which such materials are now being produced on an industrial scale at the Donetsk Chemical Reagents Factory.Translated from Poroshkovaya Metallurgiya, No. 3(243), pp. 94–100, March, 1983.