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Shear Melting and High Temperature Embrittlement: Theory and Application to Machining Titanium

Published online by Cambridge University Press:  14 July 2016

Graeme J Ackland ,
Con Healy ,
Sascha Koch ,
Florian Brunke  and
Carsten Siemers
Graeme J Ackland*
Affiliation:
School of Physics, University of Edinburgh, Edinburgh EH9 3FD Scotland, UK.
Con Healy
Affiliation:
School of Physics, University of Edinburgh, Edinburgh EH9 3FD Scotland, UK.
Sascha Koch
Affiliation:
School of Physics, University of Edinburgh, Edinburgh EH9 3FD Scotland, UK.
Florian Brunke
Affiliation:
Technische Universitaet Braunschweig. IfW, Langer Kamp 8, 38106 Braunschweig, Germany
Carsten Siemers
Affiliation:
Technische Universitaet Braunschweig. IfW, Langer Kamp 8, 38106 Braunschweig, Germany
*
*(Email: [email protected])
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Abstract

We show that alloying with rare earth metals (REMs) can dramatically improve the machineability of a range of titanium alloys, even though the REM is not incorporated in the alloy matrix. The mechanism for this is that under cutting, shear bands are formed within which the nano-precipitates of REM are shear mixed. This lowers the melting point such that the mechanism of deformation changes from dislocation mechanism to localised amorphisation and shear softening. The material then fractures along the thin, amorphous shear-band. Outside the shear band, the REM remains as precipitates. The new alloys have similar mechanical properties and biocompatibility to conventional materials.

Keywords

machiningTiLa
Type
Articles
Information
MRS Advances , Volume 1 , Issue 35: Materials Design , 2016 , pp. 2477 - 2482
Copyright
Copyright © Materials Research Society 2016 

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References

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