SciELO - Scientific Electronic Library Online

 
vol.111 número3Microstructure evolution in Ti-6Al-4V alloy during hydrogen dosing at elevated temperatureThe influence of Mn on the tensile properties of SSM-HPDC Al-Cu-Mg-Ag alloy A201 índice de autoresíndice de assuntospesquisa de artigos
Home Pagelista alfabética de periódicos  

Serviços Personalizados

Artigo

Indicadores

Links relacionados

  • Em processo de indexaçãoCitado por Google
  • Em processo de indexaçãoSimilares em Google

Compartilhar


Journal of the Southern African Institute of Mining and Metallurgy

versão On-line ISSN 2411-9717
versão impressa ISSN 0038-223X

J. S. Afr. Inst. Min. Metall. vol.111 no.3 Johannesburg  2011

 

TRANSACTION PAPER

 

The use of titanium hydride in blending and mechanical alloying of Ti-Al alloys

 

 

I.A. MwambaI, II; L.H. ChownI, II

IAdvanced Materials Division, Mintek
IIDST/NRF Centre of Excellence in Strong Materials, University of the Witwatersrand

 

 


SYNOPSIS

Titanium sponge, which is almost pure titanium, is extremely ductile and not easily processed into titanium powder. One method of producing powder is the hydride-dehydride (HDH) process, where titanium sponge is hydrided to form brittle titanium hydride (TiH2). Titanium hydride is easily milled to produce powder and is then dehydrided to form Ti powder.
In this work, titanium hydride powder obtained from titanium sponge was used as a starting material for blending and mechanical alloying with elemental powders. Firstly, titanium hydride powder was blended with aluminium elemental powder to produce a homogenized powder, which was then compacted and sintered to produce powder metallurgy compacts. Secondly, titanium hydride powder was mechanically alloyed with aluminium elemental powder and then compacted. The mechanically alloyed powder was characterized in terms of particle size distribution, morphology and microstructure. In both blending and mechanical alloying, the green compacts were characterized by assessing the green density, while the sintered compacts were characterized by their sintered density, microstructure, and hardness. The two processes have resulted in the formation of TiAl3 intermetallic compound.
It was established that by simple mixing and homogenizing, titanium hydride can be used as a starting material to produce powder metallurgy components in which porosity is a benefit rather than a problem, much akin to metallic foams.
From the products obtained in the TiH2-Al system, it appears that titanium hydride can be used as a precursor in mechanical alloying. However, the possible formation of complex hydrides may introduce detrimental properties, and needs to be further investigated. For the production of non-porous components, it would be advisable to dehydrogenate the TiH2 powder before milling i.e. producing titanium powder by the hydride-dehydride (HDH) method.

Keywords: Mechanical alloying, titanium hydride, titanium aluminide and blending


 

 

“Full text available only in PDF format”

 

 

References

1. ELIZABETH, J. Dictionary of inorganic compounds, Chapman & Hall, 2-6, Boundary Row, London, SEI 8HN, UK, pp. 3376.         [ Links ]

2. REILLY, J.J. Chemistry of intermetallic hydrides, Symposium for Hydrogen Storage Materials, Batteries and Chemistry, Conf. Proc. 180th Meeting of the Electrochemical Society, Phoenix, Arizona, 1991, cited in www.osti.gov/bridge/servlets/purl/6084207-YhGxqp/, 25 May 2010.         [ Links ]

3. ELLERN, H. Military and civilian pyrotechnics, Chemical publishing Company Inc., New York, 1968, pp. 17-82.         [ Links ]

4. ELIEZER, D., TAL-GUTELMACHER, E., and BOELLINGHAUS, TH. Hydrogen Embrittlement in Hydride- and Non-Hydride Forming Systems - Microstructural/Phase Changes and Cracking Mechanisms, Conf. Proc. 11th Int. Conference on Fracture (ICF11), Turin, Italy, March 20th-25th, 2005, pp. 123-130.         [ Links ]

5. TAL-GUTELMACHER, E. and ELIEZER, D. The hydrogen embrittlement of titanium-based alloys, JOM, 2005, pp. 46-49.         [ Links ]

6. ELIEZER, D., ELIAZ, N., SENKOV, O.N., and FROES, F.H. Positive effects of hydrogen in metals, Materials Science & Engineering, A280, 2000, pp. 220-224.         [ Links ]

7. FROES, F.H., SENKOV, O.N., and QAZI, J.I. Hydrogen as a temporary alloying element in titanium alloys: thermohydrogen processing, International Materials Reviews, vol. 49, no. 3-4, 2004, pp. 227-245.         [ Links ]

8. SELVA VENNILA, R., DURYGIN, A., MERLINI, M., WANG, Z., and SAXENA, S.K. Phase stability of TiH2 under high pressure and temperatures, International Journal of Hydrogen energy, vol. 33, 2008, pp. 6667-6671.         [ Links ]

9. ASAVAVISITHCHAI, S. and KENNEDY, A. Decomposition behaviour of asreceived and heat treated TiH2 powders, cited in www2.mtec.or.th/th/seminar, 6 June 2010.         [ Links ]

10. LIDE, D.R. Handbook of chemistry and physics, CRC Press, Taylor & Francis Group, 2007-2008, pp. 4-96.         [ Links ]

11. CROWE, P. Titanium hydride dramatically lowers manufacturing cost of titanium parts, http://thekneeslider.com/archives/2009/08/19titanium,hydride-dramatically-lowers-manufacturing-cost-of-titanium-parts, cited 2010/06/03.         [ Links ]

12. CARREŇO-MORELLI, E., KRSTEV, W., ROMEIRA, B., RODRIQUEZ-ARBAIZAR,M., BIDAUX, J.-E., and ZACHMANN, S. Powder injection moulding of titanium TiH2 powders, Nabertherm, website: www.nabertherm.com, accessed 2010/06/04        [ Links ]

13. IVASISHIN, O.M., DEMIDIK, A.N., and SAVVAKIN, D.G. Use of titanium hydride for the synthesis of titanium aluminides from powder materials, Powder Metallurgy and Ceramics, vol. 38, 9-10, 1999, pp. 482-487.         [ Links ]

14. DU, Z., ZHANG, X., WANG, Q., and LUO, S. Deformation behaviour of aluminium alloy during semi-solid compression, Solid state phenomena, vol. 141-143, 2008, pp. 647-652.         [ Links ]

Creative Commons License Todo o conteúdo deste periódico, exceto onde está identificado, está licenciado sob uma Licença Creative Commons