Role of beta-stabilizing elements on the microstructure and mechanical properties evolution of modified PM Ti surfaces designed for biomedical applications

ABSTRACT

This work focuses on the evaluation of modified surfaces on Ti produced by powder metallurgy. These newly designed surface modifications are achieved by deposition and diffusion of a stable aqueous suspension prepared in one case from micro-sized Nb powder (Ti β-stabilizer element) and in another case from Nb plus the addition of ammonium chloride, NH₄Cl, (thermo-reactive diffusion process). Different design parameters such as diffusion element (Nb or Mo), state of the Ti substrate (green or sintered) and the treatment process (diffusion or thermo-reactive diffusion) lead to all the surface-modified materials, GreenTi–Nb, SintTi–Nb and Ti–Nb_NH4Cl, GreenTi–Mo, SintTi–Mo and Ti–Mo_NH4Cl. The modified Ti surfaces present a gradient in composition and microstructure (β / α+β / α phases) resulting in an improvement in some of their mechanical properties: (1) higher micro-hardness in all the modified materials and (2) lower elastic modulus (more similar to that of the human bone) in those without NH₄Cl.

Invited keynote papers from EuroPM2017, Milan.

KEYWORDS:

• Titanium
• surface-modification
• powder technology
• microstructural-gradient
• elastic modulus
• hardness

Disclosure statement

No potential conflict of interest was reported by the authors.

Notes on contributors

J. Ureña was born on November 26th, 1990 in Jaén/Spain. She studied chemistry at the University of Jaén from 2008 to 2012. Now, she is working in her PhD in material engineering from 2014 at the Group of Powder Metallurgy (GTP) of the University Carlos III of Madrid.

E. Tejado was born on September 24th, 1985 in Cáceres/Spain. She studied Building and Materials Engineering at the University of Extremadura. In 2017 she finished her PhD at the Materials Science Department of the Technical University of Madrid where she is actually working as an Assistant Professor.

J. Y. Pastor was born on October 26th, 1965 in Madrid/Spain. He studied physics and physics of materials in the Complutense University of Madrid from 1983 to 1988. In 1993, he finished his PhD in the Complutense University of Madrid. Now, he is Full Professor of Material Science and Engineering and Director of the Materials for the Future Cluster of the International Campus of Excellence-Moncloa in the Technical University of Madrid.

F. Velasco has a PhD in Materials Science and Metallurgical Engineering in 1995 at University Politecnica of Madrid, Spain. He is professor at University Carlos III of Madrid since 1997. He has carried out research in sintered materials, corrosion and oxidation processes, adhesives, surface treatments and organic coatings.

S. Tsipas received her MEng degree in Materials Science and Engineering from Imperial College, London, United Kingdom in 2000 and completed her PhD in 2006 at the Department of Materials Science and Metallurgy in the University of Cambridge, United Kingdom. She was a post-doctoral researcher at the University Complutense of Madrid, Spain in 2006–2008. Since 2008 she works at University Carlos III of Madrid, Spain.

A. Jiménez-Morales is PhD in Industrial Technology (1999) from University Carlos III of Madrid, Spain. She is member of the Powder Metallurgy Group of the University Carlos III of Madrid. She has received the Award of Excellence in 2015 by the Social Council of the UC3M, the Santander Bank and Airbus. Her research is mainly focused on coatings and surface treatments, and powder injection molding processing.

E. Gordo is PhD in Mining Engineering (1998) from Technical University of Madrid, Spain. She obtained recently a full professor position at the University Carlos III of Madrid, Spain, where she was associated professor from 2003. Her research is mainly focused in the design and processing of titanium alloys and hardmetals by powder metallurgy.

ORCID

E. Tejado http://orcid.org/0000-0002-5240-6702

S. Tsipas http://orcid.org/0000-0001-7590-2795

E. Gordo http://orcid.org/0000-0002-2869-1363

Additional information

Funding

The authors would like to thank the funding provided for this research by the Regional Government of Madrid (program MULTIMAT-CHALLENGE-CM, ref. S2013/MIT-2862), and by the Ministry of Economy and Competitiveness of Spain (program MINECO, ref. PCIN-2016-123 and Ramón y Cajal contract RYC-2014-15014).