Compaction Kinetics with Liquid-Phase Sintering of W – Ni – Sn Pseudoalloys

Nizhenko, V. I.; Skorokhod, V. V.

doi:10.1023/b:pmmc.0000048130.83148.dd

Cited by 11 publications

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“…In comparing experimental results obtained in [6] for a specimen containing 10 mass% liquid phase and those found in the present work for specimens with the same liquid phase content, but with a smaller amount of nickel, it was detected that the final porosity after sintering for the first specimens (3.4%) is higher than for the second (almost zero). Correspondingly the diffusion coefficient evaluated from kinetic coefficients for the first specimens was less than for the second (0.11 ⋅ 10 −5 cm 2 /sec compared with 0.36 ⋅ 10 −5 cm 2 /sec with L 0 = 3 µm).…”

Section: Equation (1) May Be Obtained By Integrating the Expressionsupporting

confidence: 64%

“…Correspondingly the diffusion coefficient evaluated from kinetic coefficients for the first specimens was less than for the second (0.11 ⋅ 10 −5 cm 2 /sec compared with 0.36 ⋅ 10 −5 cm 2 /sec with L 0 = 3 µm). Here the estimated solubility of tungsten in molten nickel-tin is lower in the specimens tested in the present work compared with data in [6]. However, a specific tendency was observed for the increase in diffusion coefficient with an increase in solid metal solubility in the melt (at least this correlation is observed with dissolution of transition metals in molten aluminum [13]).…”

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confidence: 51%

“…The research method (dilatometric), the original materials, and the heating regime during sintering have been described in [6]. Dilatograms were recorded for specimens containing (according to the charge) 4, 6, 8, and 10 mass% liquid phase.…”

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Features of W - Ni - Sn Pseudoalloy Compaction during Sintering in the Presence of a Liquid Phase

Nizhenko

Petrishchev

Skorokhod

2005

Powder Metall Met Ceram

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V. I. Nizhenko, V. Ya. Petrishchev, and V. V. Skorokhod UDC 621.762 The kinetics of compaction with liquid-phase sintering for pseudoalloys of the system W − Ni − Sn are studied with molten Ni − Sn as the liquid phase. Experimental data are satisfactorily described by a kinetic equation on porosity − time coordinates. Time dependencies for compaction rate and viscosity are established for these alloys.There are systems within which a small addition of alloying admixture rapidly accelerates compact shrinkage in the initial stage of solid-phase sintering. This effect is observed most clearly on adding nickel to a compact made from tungsten powder [1][2][3][4][5]. It is interesting to study the effect of nickel on compaction kinetics for tungsten compacts during sintering in the presence of a liquid phase whose appearance temperature is markedly lower than that for nickel.Compaction kinetics have been studied [6] during liquid-phase sintering of composites of the system W − Ni − Sn containing from 3 to 10 mass% liquid phase of eutectic composition (67.5 mass% Ni + 32.5 mass% Sn). The Ni − Sn system has another eutectic (57 mass% Ni + 43 mass% Sn) with a melting temperature of 1160°C formed with intermetallics Ni 3 Sn and Ni 3 Sn 2 . We have studied compaction kinetics for W − Ni − Sn pseudoalloys within which this

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Section: Equation (1) May Be Obtained By Integrating the Expressionsupporting

confidence: 64%

Section: Equation (1) May Be Obtained By Integrating the Expressionmentioning

confidence: 51%

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Features of W - Ni - Sn Pseudoalloy Compaction during Sintering in the Presence of a Liquid Phase

Nizhenko

Petrishchev

Skorokhod

2005

Powder Metall Met Ceram

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“…Moreover, the production of dense compacts by liquid-phase sintering at relatively low temperatures is very promising. The kinetics and mechanism of liquid-phase sintering of tungsten were studied in [1][2][3][4][5][6].This paper deals with x-ray diffraction analysis of composites compacted and sintered from W, Co, and Sn powders for 1 h at 1200°C in hydrogen followed by cooling in a furnace. The composites were as follows, wt.%: 90 W-7 Co-3 Sn, 90 W-3 Co-7 Sn, and 90 W-2 Co-8 Sn.…”

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X-ray analysis of the phase composition of liquid-phase interaction products of W, Co, and Sn powders

Chuprina

Shalya

2008

Powder Metall Met Ceram

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X-ray analysis (in Cu and Mo radiation) is used to examine the phase composition of pseudoalloys for the first time. The pseudoalloys are formed in the liquid-phase sintering of W, Co, and Sn powders in hydrogen at 1200°C. After cooling, all pseudoalloys contain tungsten (intensive reflections) and W 6 Co 7 (weak reflections) phases, γ′-phases of Co 3 Sn 2 , and CoSn 2 .Studying the liquid-phase sintering of refractory metal powders is of great importance. Moreover, the production of dense compacts by liquid-phase sintering at relatively low temperatures is very promising. The kinetics and mechanism of liquid-phase sintering of tungsten were studied in [1][2][3][4][5][6].This paper deals with x-ray diffraction analysis of composites compacted and sintered from W, Co, and Sn powders for 1 h at 1200°C in hydrogen followed by cooling in a furnace. The composites were as follows, wt.%: 90 W-7 Co-3 Sn, 90 W-3 Co-7 Sn, and 90 W-2 Co-8 Sn.Diffraction patterns of the sintered samples were taken in molybdenum radiation using a DRON-3 diffractometer. Simultaneously, x-ray patterns of the starting powders and those produced from the composites were taken in copper radiation. The x-ray patterns were taken in a Debye camera of 150-mm diameter. Tables 1-3 summarize the results from analysis of x-ray patterns and some diffraction patterns and present sin 2 ϑ (ϑ is the Bragg angle) and their relative intensities visually evaluated on a ten-point scale for each reflection.To identify x-ray and diffraction patterns, we used data on the crystal lattices of potential (sought) phases [7-10]. Based on these data, typical sin 2 ϑ values were calculated for each phase. The phase analysis was carried out by comparing experimental and calculated sin 2 ϑ values. Tables 1-3 give reflection indices (hkl) of the phases thus found.Using the relevant quadratic formula [8], we calculated the lattice parameters for all hkl typical of this phase. The calculated values of each parameter matched, so it was confirmed that the analysis was correct.According to [9], tin does not interact with tungsten. Therefore, composites formed in the sintering of W, Co, and Sn powders may contain compounds resulting from the interaction of tungsten with cobalt or cobalt with tin.The W-Co phase diagram [9, 10] is evidence of two compounds: Co 3 W (25 at.% W) and W 6 Co 7 (46 at.% W). Since the amount of tungsten is maximum in the composites (90%), the presence of W 6 Co 7 would be naturally

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Preparation of wear-resistant powder materials based on iron by hot stamping in the presence of a liquid phase

et al. 2011

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Compaction Kinetics with Liquid-Phase Sintering of W – Ni – Sn Pseudoalloys

Cited by 11 publications

References 8 publications

Features of W - Ni - Sn Pseudoalloy Compaction during Sintering in the Presence of a Liquid Phase

Features of W - Ni - Sn Pseudoalloy Compaction during Sintering in the Presence of a Liquid Phase

X-ray analysis of the phase composition of liquid-phase interaction products of W, Co, and Sn powders

Preparation of wear-resistant powder materials based on iron by hot stamping in the presence of a liquid phase

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