Abstract
We have examined the effects of temperature, stress, and grain size on the creep process including creep strain, crystal structure, dislocations and diffusions of nanocrystalline NiAl alloy through molecular dynamics simulations. A smaller grain size accelerates the creep process due to the large volume fraction of grain boundaries. Higher temperatures and stress levels also speed up this process in terms of dislocation changes and atom diffusion. In both primary creep and steady-state creep stages, atomic diffusion at the grain boundary could be seen and the dislocation density increased gradually, indicating that the creep mechanism at these stages is Coble creep controlled by grain boundary diffusion while accompanied by dislocation nucleation. When the model enters the tertiary creep stage, it can be observed that the diffusion of atoms in the grain boundary and in the crystal and the dislocation density gradually decreases, implying that the creep mechanisms at this stage are Coble creep, controlled by grain boundary diffusion, and Nabarro–Herring creep, controlled by lattice diffusion.
Highlights
The intermetallic compound NiAl is of great importance due to its unique characteristics, including its high melting point, low density, outstanding thermal conductivity and excellent oxidation resistance [1,2,3]
Raj et al [4] have assessed the creep mechanism of fine-grained polycrystalline NiAl under different creep stages and found that the experimental creep rates are several orders of magnitude lower than those predicted by theoretical models
For the first time, we investigated the effects of temperature, stress and grain size on on the creep of nanocrystalline NiAl alloy through Molecular dynamics (MD) simulations
Summary
The intermetallic compound NiAl is of great importance due to its unique characteristics, including its high melting point, low density, outstanding thermal conductivity and excellent oxidation resistance [1,2,3]. Xiao et al [5] have adopted mechanical alloying and high-temperature hot pressing processes to synthesize NiAl nanocrystalline materials. The creep process and creep mechanism of nanocrystalline NiAl alloys (grain size ≤10 nm) remains largely unknown. For the first time, we investigated the effects of temperature, stress and grain size. For the first time, we investigated the effects of temperature, stress and grain size on on the creep of nanocrystalline NiAl alloy (grain size ≤10 nm) through MD simulations. We have the creep of nanocrystalline NiAl alloy (grain size ≤10 nm) through MD simulations. Was calculated to obtain the values regarding atomic diffusion [24].mean square displacement deformation process, simulated by Wigner–Seitz defect analysis [23]. The (MSD) was calculated to obtain the values regarding atomic diffusion [24]
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