Influence of carbon on the structure and properties of TiC-WC-TaC-Co sintered carbides

Conclusions Specimens of TT7K12 alloy with a combined carbon content of 0.92–0.97 and of TT20K9 alloy of 0.91–0.95 of stoichiometric have a WC+(Ti, W, Ta)C+Co three-phase structure. The width of the WC+(Ti, W, Ta)C+Co three-phase area is 0.26-0.25% C. With a reduction in carbon content the grain size of the WC and (Ti, W, Ta)C phases decreases.An increase in carbon content in the alloy within the limits of the area of three-phase equilibrium leads to a decrease in the lattice parameter of the cobalt phase caused by the decrease in the content of tungsten and titanium dissolved in it, which corresponds to the results of earlier investigations of the WC-Co, TiC-WC-Co, and TiC-WC-TaC-Co systems.Alloys with a combined carbon content of 0.92–0.95 of stoichiometric possess the best combination of properties with the maximum coefficient of life and high bend strength.Translated from Poroshkovaya Metallurgiya, No. 10(286), pp. 62–66, October, 1986.     

Mechanical properties and microstructure of sintered titanium alloys

Conclusions A study was made of the mechanical properties and microstructure of titanium alloys in the sintered state. The influence of alloying elements was evolved. It was established that for alloys used in the sintered state it is favorable to use vanadium, aluminum, and molybdenum as alloying elements.The titanium alloy containing 3% Al and 3% V, made by the method of combined reduction of oxides of TiO₂, Al₂O₃, V₂O₅ by calcium hydride (_B-774.2 MN/m², -15%, -26%, a_k-25.4 joules/cm²) and also the alloy Ti+3% Al+3% V+2% Mo (_B-857.5 MN/m², -14.3%,-27%, a_k-24.5 joules/cm²) can be recommended for the manufacture of components by methods of powder metallurgy.     

Deformation properties of sintered tungsten-based heavy alloys

The deformation properties of tungsten-based sintered alloys are studied. Plasticity diagrams are plotted for these alloys at deformation temperatures up to 900°C and various state-of-stress schemes. The properties of the tungsten-based sintered alloys are determined during alternating deformation. The joint action of the temperature (up to 900°C) and the state of stress on the ductility of the tungsten-based sintered alloys is analyzed. The results obtained are used to simulate damage accumulation for various methods of strain hardening of heavy alloys (rotational reduction, hydraulic forging, rolling in multiroll passes). Hydraulic forging is considered, and the limiting reductions are determined using the condition of impossible irreversible metal microfracture.     

Properties of sintered hard alloys WC-Ni with inhomogeneous structure

Translated from Poroshkovaya Metallurgiya, No. 11(311), pp. 28–33, November, 1988.     

Phase structure and electrochemical properties of laser sintered La2MgNi9 hydrogen storage electrode alloys

Phase structure and electrochemical properties of laser sintered La2MgNi9 alloys were studied. The sintered alloys contained a main phase, LaNi5, and a ternary La-Mg-Ni phase, with a PuNi3 structure and a small amount of LaMgNi4. The ternary La-Mg-Ni phase with a PuNi3 structure had the composition of La1.8Mg1.2Ni9 and La2MgNi9, for alloys laser sintered at 1000 and 1400 W, respectively. Owing to further reactions between LaNi5 and LaMgNi4, the amount of the PuNi3 phase increased for alloys sintered at 1400 W. Both alloys had good activation property (three charge/discharge cycles). The discharge capacities of the sintered alloys were 321.8 and 344.8 mAh/g, respectively. Compared with the alloy laser sintered at 1000 W, the poor cyclic stability of the alloy sintered at 1400 W was mainly attributed to the lower corrosion resistance of the La2MgNi9 phase.     

Features of the effect of nanodispersed additives on the sintering process and properties of powdered cobalt alloys

Some questions on the development of the cobalt-based composite material dispersion-hardened by nanoparticles using powder metallurgy are considered. The powders of WC, ZrO₂, and Al₂O₃ are used as nanoparticles that harden the Co matrix. The nanoparticles are mixed with cobalt powder of extra fine grade Co in a centrifugal planetary mill. It is shown that the treatment according to the suggested mode ensures a uniform distribution of nanoparticles throughout the volume of the Co powder, which is also retained after hot pressing. The obtained dispersion-hardened Co alloy possesses high indices of mechanical and tribological properties. For example, the wear resistance of the samples of optimum composition increases by a factor of six, while the bending strength increases by 25%.     

Effect of processing factors on the mechanical properties of sintered TiC-Ni-Co-Cr alloys

Conclusions Variation in the processing parameters involved in the manufacture of a TiC-base sintered hard alloy with a Ni-Co-Cr binder changes its static strength about one and a half to twofold, its dynamic strength threefold, and its resistance to abrasive and hydroabrasive wear two- to fourfold.Translated from Poroshkovaya Metallurgiya, No. 1 (169), pp. 11–16, January, 1977.     

The effect of carbon content on the mechanical properties of tungsten carbide-cobalt hard alloys

Summary A study was made of the effect of graphite and-phase contents on the properties of VK8 alloy. It was found that, in the presence of the-phase in the alloy in the form of lakes or dendrites (lace), indicating carbon deficiency, the strength of the alloy is greatly reduced. Slight decarburization, taking the form of-phase formation along the interphase boundaries, has practically no effect on the strength of VK8 alloy. The presence of graphite in an amount of less than 0.5 vol. % has little effect on the wear resistance of VK8 alloy, and slightly raises its strength. A high graphite content substantially lowers both strength and wear resistance.     

Influence of additives of carbon nanotubes on the structure and properties of metal binders for a diamond tool

The possibility of alloying the powder alloy of the Fe-Cu-Co-Sn system with multilayered carbon nanotubes (MCNTs) in order to form a dispersion-hardened composite material with improved mechanical and tribological properties, which can be used as a binder for a diamond cutting tool, is considered. The mixing mode of carbon nanotubes with the starting powder binder is selected. The dependence of physicochemical properties of the composite material on the MCNT content is investigated in a range of 0.01–3%. The composite binders with the optimal MCNT content at a level of 0.01% are fabricated. The alloy is characterized by improved mechanical properties; namely, hardness increases by 9–11 HRB units and the bending strength for three-point bending increases by 100 MPa.