TY  - NEWS
AU  - Zhang, Jian
AU  - Raabe, Dierk
AU  - Dippel, Ann-Christin
TI  - New mechanism reveals the secrets of a Ti alloy transformation
M1  - PUBDB-2017-12927
PY  - 2017
AB  - A new phase transformation mechanism has been described for a variation of the gum metal, an oxygen-free, β-titanium (Ti) alloy, with niobium (Nb), tantalum (Ta), and zirconium (Zr) as alloying elements. The scientists behind the discovery believe that their findings will serve as a guide for future developments of new and improved varieties of Ti-alloys. Their work is published in Nature Communications.Pure titanium undergoes a crystallographic transformation at 882°C, from the alpha (α) phase, where the atoms are in a hexagonal lattice structure (hcp), to the beta (β) phase, which exhibits a body centered cubic crystalline structure (bcc). Depending on the mixture of chemical elements that are used for the alloying, this transformation temperature can be altered significantly. Gum metals, in which the β-phase is stabilized at room temperature, are a very special class of β-titanium alloys, with very low elastic stiffness and nearly hardening-free plasticity. Contrary to other metals, gum metals do not become harder or brittle when deformed, but easily change their shape and “bend almost like honey” as Dirk Raabe, director at the Max-Planck-Institut for Iron Research (MPIE) and co-author of the article, describes. This exceptional mechanical behavior makes them very important for biomedical and aerospace applications.Understanding the underlying transformation mechanisms in Ti-alloys is considered crucial for designing gum metals or gum-metal-like materials for desired microstructures and mechanical properties.Experts from MPIE and DESY Research Center in Germany, the State Key Laboratory for Mechanical Behavior of Materials in China, and the Massachusetts Institute of Technology, led by Jian Zhang of MPIE (currently at the State Key Laboratory), have unravelled the mechanism behind a new transformation phenomenon that may explain why and how the gum metal can be deformed to such a high degree. The phase transformation appears upon fast cooling (quenching) the Ti-23Nb-0.7Ta-2Zr at.
LB  - PUB:(DE-HGF)21
UR  - https://bib-pubdb1.desy.de/record/396847
ER  -