Mechanical and Tribological Behavior of Powder Metallurgy Processed Aluminum–Graphite Composite

Russian Journal of Non-Ferrous Metals - In this research, the mechanical and tribological behavior of aluminum–graphite (Al–Gr) composite has been investigated in order to determine the...     

Regularities of Reactive Diffusion and Phase Formation in Ni ― Bi,Ni ― Zn,and Co ― Zn Binary Systems

Intermetallide layers enriched in bismuth or zinc are the first to grow in the Ni Bi, Ni Zn, and Co Zn reaction pairs. It is not found that high-symmetry phases of equiatomic composition are formed. There is not even a weak correlation between the rate of layer growth and the width of the homogeneity region for these intermetallic compounds. The main factors that determine the formation sequence for the intermetallic layers are the differences in melting point and atomic radius between the components, as well as the crystal structures of the intermetallides. The Kirkendall effect cannot be observed in the growing intermetallic layers. In that case, there is no physical basis for determining integrated diffusion coefficients.     

Effect of Rare Earths and Nitrogen on Graphite Structure of Gray Cast Iron

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Structure and Wear Resistance of Plasma-Sprayed NiCrBSiC–TiCrC Composite Powder Coatings

Powder Metallurgy and Metal Ceramics - The NTC20 and NTC40 composite powders were produced by conglomeration from the NiCrBSiC self-fluxing alloy with additions of 20 and 40 wt.% TiCrC,...     

Phase Structure and Electrochemical Properties of RE-Mg Based Composite Hydrogen Storage Alloys

Rareearth basedAB5 typealloy ,akindofhy drogenstoragealloyusedasnegativeelectrodemateri alsofthenickel/metalhydride (Ni/MH )secondarybattery ,haseasyinitialactivation ,longcyclelifeandlowcost ,butstillasmalldischargecapacity ,poorhigh ratedischargeability(HRD)andpoorpropertiesatlowtemperature[1,2 ] .Therefore ,howtoincreaseitsdischargecapacityandtoimproveotherelectrochemi calpropertiesismeaningfulbothintheoryandinpracticalapplication .Mg basedhydrogenstorageal loysareremarkablebecauseofitsr…     

Structure and Properties of Iron (Chromium Steel)–High-Carbon Ferrochrome Powder Composites

Powder Metallurgy and Metal Ceramics - The effect of production conditions on the phase composition, structure, and properties of powder materials made of iron and chromium steels (Kh17N2, Kh13M2)...     

Consolidation and Structure Formation during the Sintering of Composites Based on Nitrides of Transition Metals of Groups IV-V. Part IV. Sintering of Composite Materials of (VN,TaN) ― Ni

A study is made of the sintering of (VN, TaN) Ni composites in argon under isothermal and nonisothermal conditions. It is shown that the sintering of these materials is characterized by a reaction between the components, which is accompanied by the release of nitrogen from the nitrides and the formation of solid solutions and intermetallides based on nickel. These processes affect the rate and sign of the consolidation process. It is established that nitrides of vanadium and tantalum are sintered with nickel considerably more rapidly and at a lower temperature than nitrides of group-IV transition metals. Isothermal sintering leads to a slowing of consolidation compared to nonisothermal sintering, which can be attributed to the release of nitrogen from the nitrides and its localization in closed pores. The sintering is accompanied by an increase in the volume content of the metallic binder and a change in its phase composition (intermetallides of nickel and nickel-based solid solutions form). TaN Ni materials are characterized by a solid phase with very fine grains (1 m).     

Chromium ― Copper System: Adhesion Characteristics,Doping, the Structure of Phase Boundary and Composites

The adhesive characteristics and the formation of phase boundaries in the Cr Cu system in a vacuum of (2-4)·10^–3 Pa in the temperature range 1100-1300°C have been studied. The microstructure of composites (50:50 by mass) made by copper impregnation of porous samples of Cr electrolytic powders and Cr obtained by calcium hydride reduction. The effect of Cr, Fe, Co, Ni, Si additions on above characteristics has been investigated.     

Effect of Hot Deformation on Formation and Growth of Thermal Fatigue Crack in Chromium Wear Resistant Cast Iron

Chromium wear resistant cast iron is widelyusedin engineering, mining and power industry forits high strength,hardness and wear resistance .Inproduction process , some wear-resistant parts ser-ving in alternative stress due to rapid heating andcooling rate ofteninduces thermal fatigue andresultsinfailure .The badthermal fatigue property of chro-mium wear resistant cast iron is due to eutectic car-bides which distribute as continuous net in matrix.Recent researches showthat hot deformation can …     

Effect of Mineralizing Agent on the Phase Composition of Nanocrystalline Powder in the System ZrO2 ― Y2O3 ― CeO2

The effect of mineralizing agent (AlF₃) on microstructural rebuilding and phase transformation that occurs during heat treatment in the range 600-1000°C for powder of the composition ZrO₂ 7 mole% CeO₂ 1 mole% Y₂O₃ is studied. The original nanocrystalline powder is prepared by high-temperature hydrolysis and sol-gel technology. It is established that during heat treatment there is decomposition of the solid solution based on T-ZrO₂ by a eutectoid reaction with formation of M-ZrO₂ and Ce₂Zr₃O₁₀. The compound Ce₂Zr₃O₁₀ is retained under these conditions at 1000°C. Anisotropic crystals of different chemical composition (M-ZrO₂, Ce₂Zr₃O₁₀, -Al₂O₃) form within the sintered matrix of a solid solution based on T-ZrO₂.     

Effects of Raw Material Molar Ratio and Addition of Mg on Titanium Aluminide–Alumina Composite Formation Mechanism

Powder Metallurgy and Metal Ceramics - In this study, the effects of molar ratio of the raw materials (TiO2 and Al) and the addition of Mg on the titanium aluminide–alumina composite...     

Some Characteristic Features of Formation of Ceramics Based on Composite Powders SiC ― Si3N4 ― Si2N2O

We have studied the characteristic features of synthesis of composite powders SiC Si₃N₄ Si₂N₂O. We have investigated processes involving hot pressing of these powders without activating additives and a protective atmosphere. We consider the mechanical properties of ceramics obtained on the basis of these composite powders.     

Phase Equilibria in the Lu ― V ― B System and the Structure of the New Boride Lu1.34V1.66B6

X-ray diffraction data have been used to construct the 1070 K isothermal section of the Lu V B phase diagram. The solubility of VB₂ in LuB₂ attains 5 at.% (lattice parameters of the (Lu, V)B₂ phase of the limiting composition with the AlB₂ structure are a = 0.3238(1), c = 0.3689(1) nm). A new ternary boride has been discovered, Lu_1.34V_1.66B₆, which belongs to the Y₂ReB₆ structure type (space group Pbam, a = 0.8947(8), b = 1.1273(7), c = 0.3381(2) nm, F _hkl > 4(F), 2thetav;_max = 72.76°, N _hkl = 379, R _F = 0.0617, R _w = 0.0653) and is characterized by a statistical distribution of the Lu and V atoms in one of the structure positions.     

Structure and Wear Resistance of Coatings on Titanium Alloy and Steels Obtained by Electrospark Alloying with AlN ― ZrB2 Material

We have studied the process of electrospark alloying of titanium alloy VT6 and steels with a composite material based on AlN ZrB₂ with ZrSi₂ additive. We have established that Al₂SiO₅ and ZrSiO₄ forming in the coating directly during its formation play the role of a solid lubricant. Under optimal conditions for electrospark alloying of the titanium alloy, the coefficient of friction is 0.13, the wear is 6 m/km for a sliding velocity of 14 m/sec and a load of 2.56 MPa. Ceramics based on AlN ZrB₂ can be recommended for use as wear-resistant and corrosion-resistant coatings.