Investigation on sintering mechanism of nanoscale tungsten powder based on atomistic simulation

Moitra, Amitava; Kim, Sunglao; Kim, Seong‐Gon; Park, Seong Jin; German, Randall M.; Horstemeyer, M.F.

doi:10.1016/j.actamat.2010.03.033

Cited by 85 publications

(48 citation statements)

References 55 publications

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“…Tungsten (W) and its alloys are promising candidate materials for plasma facing applications at elevated temperatures, due to their excellent properties such as high melting point (3422 C), high density, high modulus, high resistance to thermal shock, low coefficient of thermal expansion and good high temperature strength [1,2]. However, they typically exhibit serious embrittlement in several situations [3], which limits the applications of W materials.…”

Section: Introductionmentioning

confidence: 99%

Effects of ball milling parameters on microstructural evolution and mechanical properties of W-3% Y composites

Zhao

Zhou

Tan

et al. 2015

Journal of Nuclear Materials

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Section: Introductionmentioning

confidence: 99%

Effects of ball milling parameters on microstructural evolution and mechanical properties of W-3% Y composites

Zhao

Zhou

Tan

et al. 2015

Journal of Nuclear Materials

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“…Tungsten, the metal with the highest melting point, has many unique physical properties such as high density, high hardness, low vapor pressure, low thermal expansion coefficient, and excellent thermal conductivity . Due to these outstanding properties, tungsten and its alloys have been widely applied in the fields of defense, medical, and nuclear fusion.…”

Section: Introductionmentioning

confidence: 99%

Selective Laser Melting and Remelting of Pure Tungsten

et al. 2020

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The processing of pure tungsten encounters a substantial challenge due to its high melting point and intrinsic brittleness. Selective laser melting (SLM) technique is gaining popularity and offers an excellent processing approach for refractory metals. Herein, dense pure tungsten specimens are produced by optimizing SLM processing parameters. The mechanical property of the SLM‐produced tungsten with an ultimate compressive strength of about 1200 MPa, which is obviously superior to that reported in other literature, is achieved. The increased laser energy input is instrumental in raising density and surface roughness of tungsten specimens. Interestingly, additional remelting of processed layers during SLM improves the surface quality and the microstructure and achieves the highest relative density (98.4% ± 0.5%). After laser remelting, the surface roughness is reduced by 28% and a large number of fine grains are obtained. The flow of fluids caused by remelting plays a decisive role in the formation of fine grains and the defect level. Therefore, these findings offer a new insight into SLM of pure tungsten.

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“…The high surface energy available and noble metal surface of silver also allows sintering to take place without 3 pressure being placed on the die; an added benefit for manufacturers, but one which leads to the final sintered structure containing 20-30% of pores. Although many studies have been performed on the sintering behaviour of nanoparticles [10,11], and also the mechanical properties of their sintered structures [8,9,12,13], there exists few detailed studies on the high temperature behaviour and stability of sintered silver at temperatures above 300 °C as a high temperature die attach (excepting [14][15]), while previous studies below 300 °C concentrate on bulk mechanical properties and statistical averages of microstructural properties [8,9,[16][17][18][19][20]. In the present work, we determine the nature and speed of microstructural changes in sintered silver throughout the 200-400 °C temperature range and investigate the atomic migration mechanisms that lead to these changes.…”

Section: Introductionmentioning

confidence: 99%

Microstructural evolution of sintered silver at elevated temperatures

Paknejad

Mansourian

Greenberg

et al. 2016

Microelectronics Reliability

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Reduction in the sintering temperature of metal powders by lowering particle size into the nanoparticle range has resulted in a new class of porous sintered joining materials.Especially promising are sintered silver based materials which can be used to form bonds between wide-bandgap semiconductor die and circuit boards for use in high temperature applications. This work shows that for these materials the exterior sintered silver surface oxidizes preventing surface morphology changes, while the interior pore surfaces of the porous silver remain largely oxide-free. These pore surfaces facilitate fast atomic movement resulting in grain growth and changes in the internal microstructure.Morphology changes in the temperature range 200-400 °C are presented both as statistical averages of grain size and, uniquely in this type of study, by tracking individual pores and grains. It is shown that the internal structure will undergo changes during high temperature storage in contrast to the stable outer surface. A new technique, utilizing the electromigration effect to check the relative surface mobility of atoms in the interior pores and exterior surfaces was used to support the conclusions deduced from thermal ageing 2 experiments. Finally, we speculate that the stability of the exterior surface could be reproduced in the interior if the chemistry of the paste was altered to allow formation of a passivating layer on the interior pores during the final stages of the sintering process, resulting in formation of a stable die attach material for applications of up to 400 °C, for which there is an urgent need.

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Investigation on sintering mechanism of nanoscale tungsten powder based on atomistic simulation

Cited by 85 publications

References 55 publications

Effects of ball milling parameters on microstructural evolution and mechanical properties of W-3% Y composites

Effects of ball milling parameters on microstructural evolution and mechanical properties of W-3% Y composites

Selective Laser Melting and Remelting of Pure Tungsten

Microstructural evolution of sintered silver at elevated temperatures

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