Speaker
Mr
Mphamela Enos Baloyi
(UL)
Description
Ab initio density functional theory approach was employed to investigate the structural properties, elastic constant and phonon dispersion of B2 binary TiPt, TiCo, TiNi and TiZr shape memory alloys. We employed the plane-wave pseudopotential method within generalized gradient approximation parameterized by Perdew, Burke and Enzerhof using VASP code. These alloys have the ability to remember their shapes after deformation, and this is due to their shape memory effect and super elasticity properties. We found that the lattice parameters are in good agreement with the experimental results within 2%. Furthermore, the TiCo system is more stable B2 and displayed higher transformation temperature. The Pugh’s ratio clearly indicates that TiPt, TiCo and TiNi binary alloys are ductile (B/G>1.75) while TiZr alloy are brittle (B/G<1.75). Phonon dispersion curves shows that TiCo is vibrational stable and there are acoustic modes observed at the gamma directions while TiPt and TiNi are not due to the existence of imaginary frequencies observed along M high symmetry direction, in agreement with the literature.
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R. Modiba, CSIR rmahlangu1@csir.co.za, H.R. Chauke, UL hasani.chauke@ul.ac.za and P.E. Ngoepe phuti.ngoepe@ul.ac.za
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Primary author
Mr
Mphamela Enos Baloyi
(UL)
Co-authors
Prof.
Hasani Chauke
(UL)
Prof.
Phuti Ngoepe
(UL)
Dr
Rosinah Modiba
(CSIR)
