scholarly journals Phase Transition in Iron Thin Films Containing Coherent Twin Boundaries: A Molecular Dynamics Approach

Materials ◽  
2020 ◽  
Vol 13 (16) ◽  
pp. 3631 ◽  
Author(s):  
Binjun Wang ◽  
Yunqiang Jiang ◽  
Chun Xu
Keyword(s):  
Thin Films ◽  
Phase Transition ◽  
Molecular Dynamics ◽  
Free Surface ◽  
Transition Temperature ◽  
Film Thickness ◽  
Martensitic Phase ◽  
Martensitic Transition ◽  
Twin Boundaries ◽  
Martensitic Phase Transition

Using molecular dynamics (MD) simulation, the austenitic and martensitic phase transitions in pure iron (Fe) thin films containing coherent twin boundaries (TBs) have been studied. Twelve thin films with various crystalline structures, thicknesses and TB fractions were investigated to study the roles of the free surface and TB in the phase transition. In the austenitic phase transition, the new phase nucleates mainly at the (112)bcc TB in the thicker films. The (111¯)bcc free surface only attends to the nucleation, when the film is extremely thin. The austenitic transition temperature shows weak dependence on the film thickness in thicker films, while an obvious transition temperature decrease is found in a thinner film. TB fraction has only slight influence on the austenitic temperature. In the martensitic phase transition, both the (1¯10)fcc free surface and (111)fcc TB attribute to the new body-center-cubic (bcc) phase nucleation. The martensitic transition temperature increases with decreased film thickness and TB fraction does not influent the transition temperature. In addition, the transition pathways were analyzed. The austenitic transition obeys the Burgers pathway while both the Kurdjumov–Sachs (K–S) and Nishiyama–Wassermann (N–W) relationship are observed in the martensitic phase transition. This work may help to understand the mechanism of phase transition in the Fe nanoscaled system containing a pre-existing defect.

Martensitic Phase Transition in Magnetic Thin Films Based on Inverse Mn2FeSi Heusler Alloys

2020 ◽  
Vol 130 (1) ◽  
pp. 117-122
Author(s):  
A. B. Granovskii ◽  
E. A. Soboleva ◽  
E. A. Fadeev ◽  
I. S. Dubenko ◽  
A. Aryal ◽  
...  
Keyword(s):  
Thin Films ◽  
Phase Transition ◽  
Heusler Alloys ◽  
Magnetic Thin Films ◽  
Martensitic Phase ◽  
Martensitic Phase Transition

Signature of Austenitic to Martensitic Phase Transition in Ni2MnGa in Mn and Ni K-Edge XANES Spectra

2008 ◽  
Vol 52 ◽  
pp. 175-180 ◽  
Author(s):  
V.G. Sathe ◽  
Soma Banik ◽  
Aditi Dubey ◽  
S.R. Barman ◽  
A.M. Awasthi ◽  
...  
Keyword(s):  
Transition Temperature ◽  
Low Temperatures ◽  
Electronic States ◽  
Peak Height ◽  
Martensitic Phase ◽  
Martensitic Transition ◽  
Strong Correlations ◽  
Austenitic Phase ◽  
Martensitic Phase Transition ◽  
Edge Features

The XANES studies at Mn, Ni and Ga K-edge of Ni2MnGa compound have been carried out at room and low temperatures. The Mn K-edge and Ni K-edge spectra shows modulation in the post edge features when the sample is cooled below martensitic transition temperature. It is strongly reflected in the XANES of Mn K-edge where the peak after the edge gets totally suppressed when the sample is in martensitic phase. This peak shows a hysteretic behaviour when thermal cycling was done across the martensitic transition temperature. This clearly shows that the peak height is a measure of austenitic phase present at a particular temperature. This demonstrates the strong correlations of electronic states and crystal structures in these compounds.

scholarly journals Shear Deformation Helps Phase Transition in Pure Iron Thin Films with “Inactive” Surfaces: A Molecular Dynamics Study

Crystals ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 855
Author(s):  
Ting Ruan ◽  
Binjun Wang ◽  
Chun Xu ◽  
Yunqiang Jiang
Keyword(s):  
Thin Films ◽  
Phase Transition ◽  
Molecular Dynamics ◽  
Free Surface ◽  
Phase Transitions ◽  
Shear Deformation ◽  
Dynamics Simulation ◽  
Nanoscale Systems ◽  
Free Surfaces ◽  
Nucleation Sites

In a previous study, it was shown that the (111)fcc, (110)fcc and (111)bcc free surfaces do not assist the phase transitions as nucleation sites upon heating/cooling in iron (Fe) thin slabs. In the present work, the three surfaces are denoted as “inactive” free surfaces. The phase transitions in Fe thin films with these “inactive” free surfaces have been studied using a classical molecular dynamics simulation and the Meyer–Entel potential. Our results show that shear deformation helps to activate the free surface as nucleation sites. The transition mechanisms are different in dependence on the surface orientation. In film with the (111)fcc free surface, two body-centered cubic (bcc) phases with different crystalline orientations nucleate at the free surface. In film with the (110)fcc surface, the nucleation sites are the intersections between the surfaces and stacking faults. In film with the (111)bcc surface, both heterogeneous nucleation at the free surface and homogeneous nucleation in the bulk material are observed. In addition, the transition pathways are analyzed. In all cases studied, the unstrained system is stable and no phase transition takes place. This work may be helpful to understand the mechanism of phase transition in nanoscale systems under external deformation.

Evolution of Microstructure in the BCC-HCP Martensitic Phase Transition in Zirconium

1997 ◽  
Vol 492 ◽  
Author(s):  
G. J. Ackland ◽  
U. Pinsook
Keyword(s):  
Phase Transition ◽  
Molecular Dynamics ◽  
Plastic Deformation ◽  
Molecular Dynamics Simulations ◽  
Stacking Faults ◽  
Low Energy ◽  
Martensitic Phase ◽  
Martensitic Phase Transition ◽  
Dynamics Simulations ◽  
Evolution Of Microstructure

ABSTRACTWe report molecular dynamics simulations of the martensitic phase transition from bcc to hep in zirconium. We show the evolution of a laminated twinned microstructure, in which some plastic deformation has occurred to rotate the twins manifested as basal stacking faults. This rotation is such as to alter the twinning angle from the 60° between the hep variants to the 61.5° angle of the low energy (1011) twins. These are thus identified as a cause of microscopic irreversibility in the transition.

scholarly journals Modulating the phase transition temperature of giant magnetocaloric thin films by ion irradiation

2017 ◽  
Vol 1 (6) ◽  
Author(s):  
S. Cervera ◽  
M. Trassinelli ◽  
M. Marangolo ◽  
C. Carrétéro ◽  
V. Garcia ◽  
...  
Keyword(s):  
Thin Films ◽  
Phase Transition ◽  
Transition Temperature ◽  
Phase Transition Temperature ◽  
Ion Irradiation

Effect of high magnetic field on the two-step martensitic-phase transition in Ni2MnGa

2000 ◽  
Vol 76 (1) ◽  
pp. 37-39 ◽  
Author(s):  
Yanwei Ma ◽  
S. Awaji ◽  
K. Watanabe ◽  
M. Matsumoto ◽  
N. Kobayashi
Keyword(s):  
Magnetic Field ◽  
Phase Transition ◽  
High Magnetic Field ◽  
Martensitic Phase ◽  
Martensitic Phase Transition
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