Effect of hydrostatic pressure on thermally induced phase transformation in NiTi alloy: A molecular dynamics study
JL Wan and ZB Chen and SJ Qin and JX Shang, COMPUTATIONAL MATERIALS SCIENCE, 153, 119-125 (2018).
Molecular dynamics simulations are performed to study the influence of hydrostatic pressure P on the thermally induced phase transformations in NiTi alloy during thermal cycling between 500 K and 5 K. It is found that the martensitic transformation path shows strong dependence on the P: During cooling process, the NiTi alloy undergoes single transformation of B2 -> B19' at 0 <= P <= 3 GPa, two-step transformation of B2 -> B2 + R -> B19' at 3 < P <= 5 GPa, and B2 -> R at 5 < P <= 8 GPa. The martensite start temperature (M-s) decreases from 293 to 236 K with increasing P from 0 to 5 GPa, and the start temperature of R phase (R-s) decreases from 333 to 233 K with increasing P from 6 to 8 GPa. The shift of M-s or R-s can be explained by the Clausius-Clapeyron equation. Our work provides novel insights into the martensitic phase transformations in NiTi alloy.
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