Molecular Dynamics Simulation on Creep Behavior of Nanocrystalline TiAl Alloy

Abstract

TiAl alloy represents a new class of light and heat-resistant materials. In this study, the effect of temperature, pressure, and grain size on the high-temperature creep properties of nanocrystalline TiAl alloy have been studied through the molecular dynamics method. Based on this, the deformation mechanism of the different creep stages, including crystal structure, dislocation, and diffusion, has been explored. It is observed that the high-temperature creep performance of nanocrystalline TiAl alloy is significantly affected by temperature and stress. The higher is the temperature and stress, the greater the TiAl alloy’s steady-state creep rate and the faster the rapid creep stage. Smaller grain size accelerates the creep process due to the large volume fraction of the grain boundary. In the steady-state deformation stage, two kinds of creep mechanisms are manly noted, i.e., dislocation motion and grain boundary diffusion. At the same temperature, the creep mechanism is dominated by the dislocation motion in a high-stress field, and the creep mechanism is dominated by the diffusion creep in the low-stress field. However, it is observed to be mainly controlled by the grain boundary diffusion and lattice diffusion in the rapid creep stage.

On the Tensile Creep Deformation Behaviour of Wrought Single-phase γ-TiAl

“…Contradicting the claims of Hayes et al [8], the various plots (Figs. [1][2][3][4][5][6], in the present discussion suggest that:…”

“…A series of reports on room temperature tensile deformation behaviour of γ-TiAl alloys show that the near-γ, two phase compositions having Al contents around 48 at.% possess the highest strengths and ductilities [1]- [3], [11]- [18]. Extensive creep deformation studies have been c arried out on a number of two phase near-γ TiAI alloys produced by various processing routes [8], [19]- [29].…”

A brief discussion on the tensile creep deformation behaviour of wrought single-phase γ-TiAl

“…A series of reports on room temperature tensile deformation behaviour of c-TiAl alloys show that the near-c, two phase compositions having Al contents around 48 at.% possess the highest strengths and ductilities [1][2][3][11][12][13][14][15][16][17][18]. Extensive creep deformation studies have been carried out on a number of two phase near-c TiAI alloys produced by various processing routes [8,[19][20][21][22][23][24][25][26][27][28][29].…”

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Creep deformation behaviour in single phase c-TiAl alloy has been an extensively studied topic since the late 1970 s. A lot of literatures have reported creep behaviour of c-TiAl alloys, manufactured using different processing techniques [1][2][3][4][5][6][7]. The present discussion revisits the original work on understanding the tensile creep deformation behaviour of wrought single-phase c-TiAl alloy by Hayes et al [8] and is aimed to develop an understanding of steady state creep, through strain vs strain rate and strain vs ln(strain rate) plots.

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Temperature-Dependent Superplasticity and Strengthening in CoNiCrFeMn High Entropy Alloy Nanowires Using Atomistic Simulations

“…Further, it has also been reported that the nucleation of dislocation and twinning is often dependent on stacking fault energy in the metals. Molecular dynamics simulations are a well known technique to investigate the atomic mechanisms related to mechanical properties [5][6][7][8][9]36], phase transformation [37,38], deformation behavior [5,6,23,39,40], etc. of both the bulk and nanoscale systems.…”