Excessive porosity after liquid-phase sintering of elemental titanium powder blends

Löw, R.; Robertson, I. M.; Schaffer, G. B.

doi:10.1016/j.scriptamat.2007.01.040

Cited by 30 publications

(23 citation statements)

References 6 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In contrast to the present observations, Robertson and Schaffer reported a pronounced swelling phenomenon for Ti-Ni PM samples when sintering at temperatures above the -Ti solidus [23][24][25]. In this case, swelling was suspected to be the result of rigorous gas release, either residual hydrogen or chlorine (chloride contaminants) from the HDH-Ti powders used [23,24].…”

Section: Effects Of Powder Size and Localized Liquid Formation (Ti-ni)contrasting

confidence: 99%

“…when the green density is > 90 % of theoretical) and consequently similar swelling responses were reported as well [23].…”

Section: Effects Of Powder Size and Localized Liquid Formation (Ti-ni)supporting

confidence: 80%

“…In this case, swelling was suspected to be the result of rigorous gas release, either residual hydrogen or chlorine (chloride contaminants) from the HDH-Ti powders used [23,24]. Although the formation of liquid boosted the densification as anticipated, the rapid densification also eliminated the open porosity.…”

Section: Effects Of Powder Size and Localized Liquid Formation (Ti-ni)mentioning

confidence: 93%

“…Ti-Ni-Sn PM systems [12,[22][23][24][25], although a slightly higher compaction pressure of 400 MPa was used in those studies, along with more coarse initial elemental powder sizes. The addition of Sn improves the green density when higher contents are used (i.e.…”

Section: Powder Compaction Behaviourmentioning

confidence: 99%

See 3 more Smart Citations

A comparison of Ti–Ni and Ti-Sn binary alloys processed using powder metallurgy

Liu

Bishop

Plucknett

2015

Materials Science and Engineering: A

View full text Add to dashboard Cite

Section: Effects Of Powder Size and Localized Liquid Formation (Ti-ni)contrasting

confidence: 99%

“…when the green density is > 90 % of theoretical) and consequently similar swelling responses were reported as well [23].…”

Section: Effects Of Powder Size and Localized Liquid Formation (Ti-ni)supporting

confidence: 80%

Section: Effects Of Powder Size and Localized Liquid Formation (Ti-ni)mentioning

confidence: 93%

Section: Powder Compaction Behaviourmentioning

confidence: 99%

See 2 more Smart Citations

A comparison of Ti–Ni and Ti-Sn binary alloys processed using powder metallurgy

Liu

Bishop

Plucknett

2015

Materials Science and Engineering: A

View full text Add to dashboard Cite

“…Panigrahi et al [8] found that sintering of titanium powder in a phase region is through lattice diffusion, while sintering of titanium powder in b phase region may involve rotation of grains perhaps due to the fine grains and high sintering temperature. Panigraphi [9] and Low et al [10] showed that alloying element can accelerate the sintering of titanium powder or cause formation of giant pores. Khan et al [11] used high velocity powder compacting technique to compact Ti-6Al-4V (wt pct) alloy powder and found that with a high ram velocity, a relative high density of~86 pct can be achieved.…”

Section: Introductionmentioning

confidence: 99%

The Tensile Mechanical Properties of Thermomechanically Consolidated Titanium at Different Strain Rates

Liang

Jia

et al. 2015

Metall Mater Trans A

View full text Add to dashboard Cite

The microstructures, tensile mechanical properties, and fracture behavior of a commercially pure (CP) titanium disk (called PF/Ti disk) and a CP titanium bar (called PE/Ti bar) made by powder compact forging (PCF) and powder compact extrusion (PCE) respectively have been studied. With increasing the strain rate from 10 À4 to 10 À1 s À1 , the yield strength of the PF/Ti disk and PE/Ti bar increased from 708 to 811 MPa and from 672 to 764 MPa, respectively; their UTS increased from 824 to 1009 MPa and from 809 to 926 MPa, respectively, and their elongation to fracture decreased from 21 to 8 pct and from 25 to 17.8 pct, respectively. With a low strain rate of 10 À4 s À1 , the PF/Ti disk did not show any cavities at unbonded or weakly bonded interparticle boundaries, but the PE/Ti bar showed a small number of cavities with sizes of around 1 lm. With a high strain rate of 10 À2 s À1 , the PF/Ti disk showed a small number of cavities with sizes in the range of 0.1 to 0.5 lm, while for the PE/Ti bar, the cavities grew into microcracks of up to 20 lm long. The findings suggest that close to 100 pct of consolidation is rapidly achieved by PCF at 1573 K (1300°C) and PCE at 1523 K (1250°C), respectively, possibly due to the dissolution of the particle oxide surface films during heating and rapid diffusion bonding between the fresh particle surfaces during PCF and PCE.

show abstract

Sintering of Titanium with Yttrium Oxide Additions for the Scavenging of Chlorine Impurities

Löw

Qian

Schaffer

2012

Metall Mater Trans A

View full text Add to dashboard Cite

Chloride impurities in titanium powders are extremely difficult to remove and present a longstanding problem in titanium powder metallurgy. We show that the detrimental effects of chlorides on the sintering of titanium can be mitigated with trace additions of yttrium oxide, which has a high affinity for the normally volatile species and forms highly stable oxychloride reaction products. Compacts that would otherwise exhibit gross swelling and excessive porosity due to chloride impurities can be now sintered to near full density by liquid phase sintering. The potency of yttrium oxide additions is observable at levels as low as 500 ppm. The scavenging of chlorine by Y 2 O 3 appears to be independent of alloy composition and sintering regime. It is effective when used with high-chloride powders such as Kroll sponge fines but ineffective when used with powders containing NaCl impurities or during solid-state sintering. The identification of highly potent chlorine scavengers may enable the future development of chloride-tolerant powder metallurgy (PM) alloys aimed at utilizing low-cost, high-chloride powder feedstocks.

show abstract

Excessive porosity after liquid-phase sintering of elemental titanium powder blends

Cited by 30 publications

References 6 publications

A comparison of Ti–Ni and Ti-Sn binary alloys processed using powder metallurgy

A comparison of Ti–Ni and Ti-Sn binary alloys processed using powder metallurgy

The Tensile Mechanical Properties of Thermomechanically Consolidated Titanium at Different Strain Rates

Sintering of Titanium with Yttrium Oxide Additions for the Scavenging of Chlorine Impurities

Contact Info

Product

Resources

About