Effect of powder particle size on the growth of titanium compacts during liquid-phase sintering with aluminum

Савицкий, А. П.; Burtsev, N. N.

doi:10.1007/bf00801568

Cited by 16 publications

(5 citation statements)

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“…The HDH powder reacts faster with liquid aluminium, then pores are created and are surrounded by intermetallics at the sites where the aluminium particles were. A study by Savitskii and Burtsev [30] showed that the increase in titanium particle size above 45 μm caused additional swelling because of the stress in the solid intermetallic layer that grows around the titanium particles. This present study uses a finer titanium powder (e.g.…”

Section: Discussion Of Ball Milled Powders With Luminiummentioning

confidence: 99%

“…The formation of intermetallics occurs at the surface of the titanium particles and therefore depends on the size of the particles. Savitskii and Burtsev [30] found that by increasing the titanium particle size above 45 μm, the growth of the intermetallic layer on the titanium particles caused the specimen to swell. The effect of LPS is largely controlled by the diffusion between the liquid and solid phases at the solid particle surface, and the effect on densification of reduced particle size, created by ball milling, has not yet been studied.…”

Section: Fig 1 Diffusion Between Liquid Aluminium and Titaniummentioning

confidence: 99%

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The effects of ball milling and the addition of blended elemental aluminium on the densification of TiH2 power

Schumann

Silvain

Bardet

et al. 2016

Materials Chemistry and Physics

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International audiencePowder production and sintering processes of titanium powder metallurgy are studied in order to reduce the cost of manufacturing titanium parts. The direct sintering of TiH2 simplifies powder processing and helps densification during sintering. The effects of ball milling have been shown to improve the dehydrogenation of TiH2, which during sintering, causes the earlier dissolution of the oxide layer surrounding the solid titanium particles, allowing solid diffusion to occur earlier. The combined effect of reduced particle size and increased dehydrogenation of ball milled TiH2 are studied here during sintering, in order to understand their roles during densification. TiH2 ball milled for various durations is vacuum hot press sintered at 700–900 °C. The density, microstructure and hardness of the fabricated titanium specimens are also studied. The effects of ball milled powder on the introduction of blended elemental aluminium are studied in comparison with a commercial titanium powder. The increase in ball milling duration of TiH2 powders to reduce particle size causes faster densification and dehydrogenation, with a finer uniform microstructure. When using fine ball milled powder with aluminium, the formation of Kirkendall pores through the interaction of titanium and liquid aluminium is worsened

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Section: Discussion Of Ball Milled Powders With Luminiummentioning

confidence: 99%

Section: Fig 1 Diffusion Between Liquid Aluminium and Titaniummentioning

confidence: 99%

The effects of ball milling and the addition of blended elemental aluminium on the densification of TiH2 power

Schumann

Silvain

Bardet

et al. 2016

Materials Chemistry and Physics

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“…Liquid aluminium wets Ti-Ti particle contacts, where formation of TiAl 3 forces the particles apart. 79 Numerous studies have been made of Ti-Al diffusion couples, 80 synthesis of Ti-Al IMCs [81][82][83][84][85][86] and sintering of Ti-Al alloys. 10,21,25,36,40,43,[87][88][89][90][91] 5 Sintered densities of Ti-6Al-4V from same sources as in Fig.…”

Section: Titanium-aluminium Alloysmentioning

confidence: 99%

“…Dilatometry curves often reveal small amounts of swelling early in the sintering heat treatment caused by melting of Al or Sn, formation of other liquids, unbalanced solid state diffusion or formation of IMC. 25,56,79,81,82,87,[101][102][103]111,118,120,122,123,[130][131][132][133][134][135][136] Extensive swelling can also occur late in the sintering heat treatment due to high gas pressure within closed pores (i.e. above y90% density).…”

Section: Other Alloysmentioning

confidence: 99%

Review of densification of titanium based powder systems in press and sinter processing

Robertson

Schaffer

2010

Powder Metallurgy

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The development of novel extractive metallurgy techniques for titanium offers the prospect of lower cost Ti powder and therefore wider application of Ti. This review is largely confined to coverage of the low cost press and sinter methods of powder metallurgy, consisting of cold pressing of mixed elemental powders followed by sintering without the application of external pressure. Cold die compaction, sintering behaviour and densification are reviewed in detail. Some information on powders and cold isostatic pressing is included. Microstructure, mechanical properties and applications are considered in less detail. The review deals mostly with the sintering of alloys, but there is some reference to synthesis of intermetallic compounds, such as the shape memory alloy NiTi and titanium aluminides for high temperature applications. Densification is discussed in terms of the four fundamental processing variables: compaction pressure, particle size, sintering temperature and sintering time. Other factors such as alloy composition, the form of alloying addition, type and impurity content of powders and heating rate are also considered.

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“…Progress towards sintering high density Fe 3 Al has been slow, owing to the mismatch in diffusion and solubility rates of elemental Fe and Al. Studies 6,7 carried out on the Ti-Al and Zn-Al systems have shown that mismatched diffusion and solubility rates promote swelling during sintering and consequently a high degree of porosity. In the Fe-Al system Kirkendall porosity forms at Al particle sites after diffusion of Al into Fe, resulting in swelling, a lowering of the average density and the formation of stable Fe-Al compounds around the pores, which prevent further densification.…”

Section: Introductionmentioning

confidence: 99%

Transient liquid phase sintering of high density Fe₃Al using Fe and Fe₂Al₅–FeAl₂powders Part 2 – Densification mechanism analysis

Xydas¹,

Salam²

2006

Powder Metallurgy

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The use of Fe 2 Al 5 -FeAl 2 prealloyed powders and heating rates .150 K min 21 overcomes the formation of density restricting Kirkendall porosity in the Fe-Al system. X-ray diffraction, electron probe micro analysis and differential thermal analysis suggest that the absence of a persistent liquid, experienced when liquid phase sintering with elemental powders, is overcome. Homogenisation is greater during heating at a rate of 20 K min 21 than for 150, 250 or 400 K min 21 and homogenous Fe 3 Al forms across the compact at temperatures below the melting point of the liquid forming constituent, indicating that a liquid will not form under such processing conditions. The maximum density achieved under the processing conditions in the present study is 92% of theoretical density. The presence of large pores shortly after liquid formation suggests that the remaining porosity is largely due to powder agglomeration during mixing.

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Effect of powder particle size on the growth of titanium compacts during liquid-phase sintering with aluminum

Cited by 16 publications

References 1 publication

The effects of ball milling and the addition of blended elemental aluminium on the densification of TiH2 power

The effects of ball milling and the addition of blended elemental aluminium on the densification of TiH2 power

Review of densification of titanium based powder systems in press and sinter processing

Transient liquid phase sintering of high density Fe₃Al using Fe and Fe₂Al₅–FeAl₂powders Part 2 – Densification mechanism analysis

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Effect of powder particle size on the growth of titanium compacts during liquid-phase sintering with aluminum

Cited by 16 publications

References 1 publication

The effects of ball milling and the addition of blended elemental aluminium on the densification of TiH2 power

The effects of ball milling and the addition of blended elemental aluminium on the densification of TiH2 power

Review of densification of titanium based powder systems in press and sinter processing

Transient liquid phase sintering of high density Fe3Al using Fe and Fe2Al5–FeAl2powders Part 2 – Densification mechanism analysis

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Transient liquid phase sintering of high density Fe₃Al using Fe and Fe₂Al₅–FeAl₂powders Part 2 – Densification mechanism analysis