Diffusion Relaxation Processes in gamma-TiAl Intermetallics studied through Mechanical Spectroscopy: An overview

  • Jose San Juan (Speaker)
  • Klein, T. (Author)
  • Helmut Clemens (Author)
  • Maria L. Nó (Author)

Activity: Talk or presentation / LecturePresentation at a scientific conference / workshop

Description

In the last decades there has been a growing interest in developing new intermetallic families,
which would we able to improve the specific performances of superalloys at high temperature.
The TNB (Ti-Al-Nb) and the TNM (Ti-Al-Nb-Mo) families were developed to fulfil the required
performances. In particular, the creep resistance should be improved and consequently the study
of the diffusion mechanisms and the associated relaxation processes becomes very useful to get a
deep understanding of the physics involved during creep. Mechanical spectroscopy, including the
measurement of the internal friction spectra and the dynamic modulus curves as a function of
temperature between 600 K and 1400 K allowed approaching the study of such processes.
Previous works on several -TiAl alloys show several relaxation processes associated with the Ti
diffusion in the 2 phase [1-3] and with the Al diffusion in the  phase [4], as well as an internal
friction background at high temperature, which is associated with the creep behaviour [2]. At
present, new generation of -TiAl, called TNM+, is being developed to improve the creep
resistance by microalloying with C and Si [5]. However, Nb and C atoms in solid solution could
have a secondary effect on creep resistance by slowing down the diffusion of Ti in the
constitutive phases.
The aim of the present work is to overview the relaxation processes associated with Ti diffusion
in 2 phase, which have been observed in several alloys with different amounts of Nb and C in
solid solution, in order to evaluate their potential influence on such relaxation processes; the
influence on Al diffusion will be also analysed. In addition, the relaxation processes observed by
internal friction are related, through the activation parameters, to the diffusion coefficients of the
different atomic species and compared with those from the literature. This comparison allows to
obtain a plot of the diffusion coefficients of Ti and Al in -TiAl, expanded towards the
temperature range close to the temperatures used in service conditions.
Period3 Jul 2023
Event titleThermec 2023
Event typeConference
LocationVienna, AustriaShow on map

Research Field

  • Wire-Based Additive Manufacturing