LOGIN TO YOUR ACCOUNT

Username
Password
Remember Me
Or use your Academic/Social account:

CREATE AN ACCOUNT

Or use your Academic/Social account:

Congratulations!

You have just completed your registration at OpenAire.

Before you can login to the site, you will need to activate your account. An e-mail will be sent to you with the proper instructions.

Important!

Please note that this site is currently undergoing Beta testing.
Any new content you create is not guaranteed to be present to the final version of the site upon release.

Thank you for your patience,
OpenAire Dev Team.

Close This Message

CREATE AN ACCOUNT

Name:
Username:
Password:
Verify Password:
E-mail:
Verify E-mail:
*All Fields Are Required.
Please Verify You Are Human:
fbtwitterlinkedinvimeoflicker grey 14rssslideshare1
Simmons, LM
Languages: English
Types: Doctoral thesis
Subjects:
The processes of phase formation and transformation in crystallised amorphous metallic\ud materials can be investigated using a wide variety of techniques. Time and temperature\ud resolved neutron and x-ray scattering offers an insight into these processes in-situ often\ud highlighting the formation of metastable and unreported phases. In this work, time- and\ud temperature-resolved synchrotron x-ray diffraction and small angle neutron scattering\ud studies are complemented with differential scanning calorimetry and transmission\ud electron microscopy to gain a complete insight into the crystallisation and subsequent\ud phase formation and transformation in two Fe-based metallic glasses: Cogo-xFe x B2o, x =\ud 20, 40 of current technological importance, and the Y-Fe system of academic interest.\ud In Co4oFe4oB2o time resolved synchrotron x-ray diffraction shows that a a-(Co,Fe) solid\ud solution is formed in isolation irrespective of isothermal temperature treatment. In\ud contrast, temperature resolved synchrotron x-ray diffraction indicates a two-stage\ud crystallisation process; primary cc-(Co,Fe) phase formation is followed by polymorphic\ud crystallisation of (Co,Fe)2B. The Johnson-Mehl-Avrami-Kolmogorov (JMAK) model\ud for isothermal phase transformation kinetics indicates one-dimensional growth with a\ud decreasing nucleation rate for the isolated a-(Co,Fe) solid solution.\ud In a direct comparison, Co6oFe2oB2 o, is shown to undergo multi-phase crystallisation\ud during both isothermal and continuously heated temperature profiles. The JMAK\ud model is in agreement to those for Co4oFe4oB2o, i.e. one dimensional growth with a\ud decreasing nucleation rate.\ud Secondly the Rare-Earth Transition Metal YeyFess is shown to crystallise from\ud elemental Y to the YFe2 Laves phase via a novel 'YFe' phase with suggested structure\ud P6/mmm, a = 12.72A and c = 8.00A. Small angle neutron scattering data modelled to a\ud Lorentzian with variable power is in agreement with previously published kinetic\ud neutron diffraction and small angle scattering data highlighting the temperature and\ud time dependence of a critical scattering event evident at the point where the whole\ud sample crystallises.\ud xiv
  • No references.
  • No related research data.
  • No similar publications.

Share - Bookmark

Cite this article