Publications
Molecular dynamics simulations of nano-indentation in lamellar γ-γ' microstructures of TiAl
A. Asaadi.
Master Thesis, Ruhr-Universität Bochum (2016)
Abstract
Different misorientations of γ phase in TiAl- at γ-γ interfaces are investigated by rotat-
ing the reference γ phase by 60° around [1 1 1]. Three possible orientations, Pseudo-twin
(PT), Rotational-boundary (RB) and True-Twin (TT) where created in adjacent to the
reference γ phase. After preparing bi-crystals and 4-lamellae models and applying nano-
indentation on them, it is observed that in bi-crystals, the PT interface model presents
a sudden drop in hardness during loading and the TT has more stable potential en-
ergy behavior than the two others. The formation of superlattice intrinsic stacking
faults(SISFs) and anti-phase boundaries(APBs) as dominant origins of events for defect
nucleation and growth in the models under loading is discussed. Moreover, when the
thickness of lamellae are reduced by 50% while the number of interfaces is increased,
an increase in hardness is observed in all the models. Finally, it is concluded that RB
and PT models have lower stability in comparison to TT model due to the higher level
of their potential. In addition, by increasing in the number of interfaces, the hardness
deviation values between bi-crystal and 4-lamellae models for PT and RB models are
higher than TT models.
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