Strengthening of Molybdenum and Tungsten Alloys with HfC

Klopp, W.D.; Raffo, Peter L.; Witzke, W. R.

doi:10.1007/bf03355708

Cited by 25 publications

(13 citation statements)

References 6 publications

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“…The pinned dislocation line will bow upon increase in the applied stress. A balance in force will be established between the line The elastic interaction energy for a solute atom at a distance T and an angle 8 fiom a dislocation can be described as [67] U(r,e) = A(sine)/T where A= (4 The term e is the atomic size mismatch factor between the solute and the solvent (matrix) atoms as shown in Table 7.1. Absolute values of this parameter are given since the interaction between dislocations and solute atoms only depends on the magnitude of this mismatch and not its sign.…”

Section: Discussionmentioning

confidence: 99%

High temperature materials technology research for advanced thermionic systems. Final report

Zee¹,

Rose²

1998

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This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or uscfulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any spccific commercial product, proctss, or KMCC by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, m mmendbtion, or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect thosc of the United States Government or any agency thereof. DISCLAIMER Portions of this document may be illegible in electronic image products. Images are produced from the best available original document. c c 1 2.. 3. 4. 5.

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Section: Discussionmentioning

confidence: 99%

High temperature materials technology research for advanced thermionic systems. Final report

Zee¹,

Rose²

1998

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“…sintering temperature. [35] The packing of nearest neighbors is Let a hypothetical bond strength (), which is the bond assumed to be in the range from 9 to 12 N * c Ϸ 0.75 ϩ 0.75 [32] Thus, the percolation model in Section III is applicable for determining the onset of distortion under gravity. At the critical point of shape distortion, the critical coordination ϩ 1 2 Ί2.25(1 Ϫ ) 2 ϩ 0.0056 number and the critical contiguity are expressed as and N * c ϭ 1.5…”

Section: Gravity Effect On Shape Distortionmentioning

confidence: 99%

Application of percolation theory in predicting shape distortion during liquid-phase sintering

Liu

Upadhyaya

German

1999

Metall Mater Trans A

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This article shows how percolation theory provides a theoretical model for the onset of shape distortion in liquid-phase sintering. The model uses an equivalent bond number per grain, with bond strength depending on the relative intergrain bond size. Based on this study, shape distortion is resisted by a rigid compact, which depends on the solid grains forming an infinite chainlike structure that spreads throughout the system. A sufficient condition requires contiguity above a critical value to form an infinite chainlike structure. The critical value is near 0.38. This is in good agreement with experimental results obtained with the W-Ni-Fe system sintered both under microgravity and on Earth. The effect of the gravitational force on the sufficient condition to avoid shape distortion is not significant. The effect of gravitational field on shape distortion becomes apparent only after the start of distortion, determining the final profile of a distorted compact.

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“…The alloying additions are done to improve the dislocation mobility of atoms, to reduce the segregation of impurities along the grain boundaries, to refine the microstructure, and, thereby, to improve the strength and ductility of tungsten [ 10 ]. Over the years, alloying elements such as rhenium [ 11 , 12 ], niobium [ 11 ], vanadium, tantalum [ 13 ], molybdenum [ 14 ], copper [ 15 ], and oxides of lanthanum and yttria [ 16 , 17 , 18 ] have been investigated with tungsten.…”

Section: Introductionmentioning

confidence: 99%

Effect of Rare Earth Metals (Y, La) and Refractory Metals (Mo, Ta, Re) to Improve the Mechanical Properties of W–Ni–Fe Alloy—A Review

et al. 2021

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Tungsten heavy alloys are two-phase metal matrix composites that include W–Ni–Fe and W–Ni–Cu. The significant feature of these alloys is their ability to acquire both strength and ductility. In order to improve the mechanical properties of the basic alloy and to limit or avoid the need for post-processing techniques, other elements are doped with the alloy and performance studies are carried out. This work focuses on the developments through the years in improving the performance of the classical tungsten heavy alloy of W–Ni–Fe through doping of other elements. The influence of the percentage addition of rare earth elements of yttrium, lanthanum, and their oxides and refractory metals such as rhenium, tantalum, and molybdenum on the mechanical properties of the heavy alloy is critically analyzed. Based on the microstructural and property evaluation, the effects of adding the elements at various proportions are discussed. The addition of molybdenum and rhenium to the heavy alloy gives good strength and ductility. The oxides of yttrium, when added in a small quantity, help to reduce the tungsten’s grain size and obtain good tensile and compressive strengths at high temperatures.

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Strengthening of Molybdenum and Tungsten Alloys with HfC

Cited by 25 publications

References 6 publications

High temperature materials technology research for advanced thermionic systems. Final report

High temperature materials technology research for advanced thermionic systems. Final report

Application of percolation theory in predicting shape distortion during liquid-phase sintering

Effect of Rare Earth Metals (Y, La) and Refractory Metals (Mo, Ta, Re) to Improve the Mechanical Properties of W–Ni–Fe Alloy—A Review

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