Titanium powders for mass production, general engineering applications

January 31, 2012

In the second of a series of exclusive reports for ipmd.net from the international conference on “Powder Processing, Consolidation and Metallurgy of Titanium”, held in Brisbane, Australia on 5-7 December, 2011, Dr David Whittaker reviews a presentation discussing the potential use of titanium powders in general engineering applications. 

Most of the high profile development activity in titanium (Ti) powder metallurgy (PM) has been aimed at niche applications in sectors such as aerospace and healthcare.

To penetrate such markets, developers of Ti PM products have been forced into trying to match the compositional and mechanical property requirements of existing wrought product standards.

In terms of composition, this has meant low levels of interstitial elements are the order of the day and, in terms of mechanical properties, double-digit tensile elongation values, in particular, have been a major target.

This has forced the use of high cost, fully pre-alloyed atomised powder grades and the use of PM processing technologies that can create full or near-to-full density products (e.g. HIP, MIM etc.).

An entirely different perspective on Ti PM material requirements was, however, taken in a paper presented by Ma Qian, The University of Queensland, on behalf of his co-authors, Ya-Feng Yang, Ming Yan, Shudong Luo and Graham Schaffer, which looked at what would be needed to stimulate the adoption of Ti PM in mass market, general engineering applications.

Initial consideration of the potential penetration of such markets indicated that:-

  • Processing by conventional die press/sinter PM would be required.
  • A low-cost powder feedstock would be needed. The target set for this development was for a material cost of US$25/kg. It was felt that such a feedstock material would have to use the elemental blended approach and should be based on the use of HDH-Ti powder. HDH-Ti powder price depends on the price of titanium sponge and it is currently available from China at around US$25/kg at, in view of the authors’ assessments, good quality levels.
  • A realistic target for tensile ductility level would need to be set, in the context of PM materials already serving these types of markets. The case was made that established PM aluminium materials had penetrated the market offering elongation levels of the order of 2% (Table 1) and that the ductility levels of many standard ferrous PM structural materials were lower still (Table 2). The US military specification MIL-DTL-46077G for wrought Ti-6Al-4V structural armour plate (Table 3) was cited in seeking an answer to the question “What ductility values would be adequate for PM Ti parts for non-fatigue-critical applications?”. On this basis, it was decided that an elongation level of 6% should be targeted in conjunction with as high as possible levels of YS and UTS.

Table 1 Current commercial PM aluminium alloys



Table 2 Mechanical properties of some standard ferrous PM grades  


Table 3 Minimum mechanical properties in MIL-DTL-46077G 



Fig.1 Thermo-Calc predictions of equilibrium solid and liquid

fractions in Ti-3Fe-xSi alloys

The feedstock material cost target did not leave a lot of elbow room for alloying element costs. The assessment of low cost options for alloying elements has eventually led the group to focus on the Ti-Fe-Si system.

Silicon (at 2.33g/cm3 density) is much lighter than titanium (4.54g/cm3), is inexpensive and small additions of silicon to titanium alloys, through ingot route metallurgy, have been shown to improve creep and oxidation resistance. However, to date, limited attention has been paid to its use in PM Ti alloys.

Based on the use of Thermo-Calc predictions (Fig. 1), DSC analyses, and microstructure examination, viable sintering treatments have been defined for Ti-Fe-Si alloys.


Fig. 2 As-sintered mechanical properties of Ti-xFe-0.5Si and Ti-xFe-1Si alloys


The as-sintered properties achieved on sintering Ti-xFe-0.5Si and Ti-xFe-1Si alloys at 1300°C for 2 hours in vacuum are illustrated in Fig. 2. The ductility values, shown in this figure, are somewhat lower than the defined target. Subsequent work has therefore been directed at the use of minor additions of other elements to improve properties. Table 4 indicates that properties in such a Ti-Fe-Si-x-y system can reach around 98% density, UTS>1000N/mm2, YS>900N/mm2 and elongation >8%.


Table 4 As-sintered properties of a range of alloys in the Ti-Fe-Si-x-y system 


At present, until the group has secured protection of its intellectual property in this development, the identities of elements x and y have not been revealed. We can look forward to the point when the protection is in place and all can be revealed.

Author: Dr David Whittaker is a consultant to the Powder Metallurgy and associated industries. Contact +44 1902 338498 email: [email protected] 

Further reading:

Titanium powder injection moulding (Ti-PIM): A review of the current status of materials, processing, properties and applications

Production of fine titanium powders via the Hydride-Dehydride (HDH) process

Titanium and titanium alloy Powder Injection Moulding: Matching application requirements

Mixing titanium MIM feedstock: Homogeneity, debinding and handling strength

Titanium parts by powder injection moulding of TiH2-based feedstocks

Advanced metal powder injection moulding for multilayered micro porous titanium components


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January 31, 2012

In the latest issue of PM Review…

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Extensive Powder Metallurgy industry news coverage, and the following exclusive deep-dive articles and reports:

  • From powder modification to rejuvenation: Fluidised Bed Reactors in metal powder production and Additive Manufacturing
  • Retech: Enabling the atomisation of reactive and refractory alloys at substantially higher levels of productivity and lower cost
  • Sustainability in Powder Metallurgy: Highlights from the 41st Hagen Symposium
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