Journal Article

PUBDB-2015-01964

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Shear Melting and High Temperature Embrittlement: Theory and Application to Machining Titanium

Healy, C. ; Koch, S. ; Siemers, C.>Extern* ; Mukherji, D.>Extern* ; Ackland, G. J. (Corresponding Author)

2015
APS College Park, Md.

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Please use a persistent id in citations: doi:10.1103/PhysRevLett.114.165501

Abstract: We describe a dynamical phase transition occurring within a shear band at high temperature and under extremely high shear rates. With increasing temperature, dislocation deformation and grain boundary sliding are supplanted by amorphization in a highly localized nanoscale band, which allows for massive strain and fracture. The mechanism is similar to shear melting and leads to liquid metal embrittlement at high temperature. From simulation, we find that the necessary conditions are lack of dislocation slip systems, low thermal conduction, and temperature near the melting point. The first two are exhibited by bcc titanium alloys, and we show that the final one can be achieved experimentally by adding low-melting-point elements: specifically, we use insoluble rare earth metals (REMs). Under high shear, the REM becomes mixed with the titanium, lowering the melting point within the shear band and triggering the shear-melting transition. This in turn generates heat which remains localized in the shear band due to poor heat conduction. The material fractures along the shear band. We show how to utilize this transition in the creation of new titanium-based alloys with improved machinability.

Note: OA

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Contributing Institute(s):

1. DOOR-User (DOOR)

Research Program(s):

1. 6G3 - PETRA III (POF3-622) (POF3-622)

Experiment(s):

1. PETRA Beamline P07 (PETRA III)
2. DORIS Beamline BW5 (DORIS III)

Appears in the scientific report 2015

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Database coverage:
; ; Current Contents - Physical, Chemical and Earth Sciences ; IF >= 5 ; JCR ; NCBI Molecular Biology Database ; SCOPUS ; Science Citation Index ; Science Citation Index Expanded ; Thomson Reuters Master Journal List ; Web of Science Core Collection

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