Effect of precursor phase transition on subsequent martensitic transformation in a Fe-10Cr alloy

2021 ◽  
pp. 160780
Author(s):  
Mingxiang Liu ◽  
Zhiming Li ◽  
Zhiping Luo ◽  
Changjiang Song ◽  
Qijie Zhai
Keyword(s):  
Phase Transition ◽  
Martensitic Transformation ◽  
Precursor Phase

scholarly journals Ab Initio Study of Martensitic Transformation in NiTiPt High Temperature Shape Memory Alloys

2021 ◽  
Vol 11 (15) ◽  
pp. 6878
Author(s):  
Xiaolan Yang ◽  
Jiaxiang Shang
Keyword(s):  
Phase Transition ◽  
Martensitic Transformation ◽  
Electronic Structures ◽  
Density Functional ◽  
Martensite Phase ◽  
Computational Results ◽  
Ab Initio Study ◽  
Functional Theory ◽  
Phase Transition Temperatures ◽  
Martensite Structure

The crystal structures and martensitic transformation of Ti50Ni50−xPtx alloys (x = 0, 6.25, 8.33, 10.42, 12.5, 18.75, 25) were studied by means of density functional theory (DFT). The computational results indicate that the lattice parameters of Ti-Ni-Pt alloys continuously increase with increasing the Pt content. It is found that at ≤ 12.5 at.% Pt, the martensite structure is monoclinic B19′ phase, and the energy differences between parent and martensite phases (ΔE) decrease slightly with a minimum observed at 6.25 at.% Pt. However, when the Pt content is increased to around 15 at.%, the most stable martensite phase is the orthorhombic B19 structure, and the ΔE increases sharply with Pt concentration. It was found that the phase transition temperatures are closely related to the energy differences ΔE between parent and martensite phases. The electronic structures of martensite B19 and B19′ phases are also discussed.

Roles for A Precursor Oxide Phase in The Siting, Shaping, and Shrinking of Oxygen Precipitates

1985 ◽  
Vol 59 ◽  
Author(s):  
P. Fraundorf
Keyword(s):  
Phase Transition ◽  
Strain Field ◽  
Oxide Phase ◽  
Induction Effect ◽  
First Order ◽  
First Order Phase Transition ◽  
Precursor Phase ◽  
Precipitate Shape ◽  
Oxygen Precipitates ◽  
First Order Phase

ABSTRACTThree separate “anomalous” effects in the precipitation of oxygen in silicon may be explained if typical poorly-crystallized platelet oxygen precipitates begin as tiny crystalline clusters. The first anomaly, sometimes referred to as the induction effect, may be explained if one postulates the existence of kinetically stable precipitate embryos (seeds) containing no more than one or two oxygen atoms. We show here that such a postulate, coupled with observations, places rather specific constraints on binding energy as a function of size for such tiny clusters. The second and third anomalies, arising in precipitate shape and retrogrowth behavior dependences, respectively, may be explained if one postulates the existence of a relatively dense precursor phase which undergoes first order phase transition, following otherwise classical rules, to the final-stage amorphous oxide normally found. In this case, both precipitate shape and strain field can be interpreted as a barometer of the interstitial ambient during key periods in a precipitate's history.

One Dimensional Model of Martensitic Transformation Solved by Homotopy Analysis Method

2012 ◽  
Vol 67 (5) ◽  
pp. 230-238 ◽  
Author(s):  
Chen Xuan ◽  
Cheng Peng ◽  
Yongzhong Huo
Keyword(s):  
Phase Transition ◽  
Martensitic Transformation ◽  
Analytical Solutions ◽  
Homotopy Analysis Method ◽  
Lagrange Equation ◽  
Nonlinear Ordinary Differential Equation ◽  
Physical Parameters ◽  
Analysis Method ◽  
Homotopy Analysis ◽  
The One

The homotopy analysis method (HAM) is applied to solve a nonlinear ordinary differential equation describing certain phase transition problem in solids. Both bifurcation conditions and analytical solutions are obtained simultaneously for the Euler-Lagrange equation of the martensitic transformation. HAM is capable of providing an analytical expression for the bifurcation condition to judge the occurrence of the phase transition, while other numerical techniques have difficulties in bifurcation analysis. The convergence of the analytical solutions on the one hand can be adjusted by the auxiliary parameter and on the other hand is always obtainable for all relevant physical parameters satisfying the bifurcation condition.

scholarly journals Observing a previously hidden structural-phase transition onset through heteroepitaxial cap response

2019 ◽  
Vol 116 (10) ◽  
pp. 4141-4146 ◽  
Author(s):  
Fanli Lan ◽  
Hongyan Chen ◽  
Hanxuan Lin ◽  
Yu Bai ◽  
Yang Yu ◽  
...  
Keyword(s):  
Phase Transition ◽  
Phase Transitions ◽  
Structural Phase Transition ◽  
Structural Phase ◽  
Second Order ◽  
Structural Phase Transitions ◽  
Lsmo Film ◽  
Precursor Phase ◽  
Micrometer Scale ◽  
Atomically Flat

Characterization of the onset of a phase transition is often challenging due to the fluctuations of the correlation length scales of the order parameters. This is especially true for second-order structural-phase transition due to minute changes involved in the relevant lattice constants. A classic example is the cubic-to-tetragonal second-order phase transition in SrTiO3(STO), which is so subtle that it is still unresolved. Here, we demonstrate an approach to resolve this issue by epitaxially grown rhombohedral La0.7Sr0.3MnO3(LSMO) thin films on the cubic STO (100) substrate. The shear strain induced nanotwinning waves in the LSMO film are extremely sensitive to the cubic-to-tetragonal structural-phase transitions of the STO substrate. Upon cooling from room temperature, the development of the nanotwinning waves is spatially inhomogeneous. Untwinned, atomically flat domains, ranging in size from 100 to 300 nm, start to appear randomly in the twinned phase between 265 and 175 K. At ∼139 K, the untwinned, atomically flat domains start to grow rapidly into micrometer scale and finally become dominant at ∼108 K. These results indicate that the low-temperature tetragonal precursor phase of STO has already nucleated at 265 K, significantly higher than the critical temperature of STO (∼105 K). Our work paves a pathway to visualize the onset stages of structural-phase transitions that are too subtle to be observed using direct-imaging methods.

Phase Transition of Ball-Milled Ni50-xMn37In13Cox (x=0,5) Alloy Powders

2014 ◽  
Vol 809-810 ◽  
pp. 377-383
Author(s):  
Xiao Ping Fei ◽  
Wei Li ◽  
Jun Liu ◽  
Feng Xu ◽  
Guo Dong Tang ◽  
...  
Keyword(s):  
Phase Transition ◽  
Martensitic Transformation ◽  
Lattice Distortion ◽  
High Temperature Annealing ◽  
Transformation Behavior ◽  
Xrd Pattern ◽  
Annealing Temperatures ◽  
Grain Sizes ◽  
Weak Reflection ◽  
One Step

Ni50-xMn37In13Cox(x=0,5) alloy powders were obtained by ball-milling from the corresponding ribbon precursors. The as-milled Ni50Mn37In13and Ni45Mn37In13Co5powders show disorderedfctandfccstructures respectively, due to the larger lattice distortion in Ni45Mn37In13Co5. DSC and XRD results show that the high-temperature annealing will lead to a one-step ordering process fromfctto Heusler structure in Ni50Mn37In13, and a two-step ordering process, includingfcctobccandbccto Heusler phase transitions in Ni45Mn37In13Co5. After annealed at 400°C and 650°C, the martensitic transformation behavior is gradually and partially restored in Ni50Mn37In13powders. As modulated by the annealing temperatures, the martensitic transformation temperatures increase with the grain sizes of Ni50Mn37In13powders. However, the martensitic transformation is almost completely suppressed in 650°C annealed Ni45Mn37In13Co5powders with only some weak reflection peaks from 7M martensitic phase observed in XRD pattern.

scholarly journals Room-temperature photo-induced martensitic transformation in a protein crystal

IUCrJ ◽  
2019 ◽  
Vol 6 (4) ◽  
pp. 619-629 ◽  
Author(s):  
Steven Dajnowicz ◽  
Patricia S. Langan ◽  
Kevin L. Weiss ◽  
Ilia N. Ivanov ◽  
Andrey Kovalevsky
Keyword(s):  
Phase Transition ◽  
Phase Transitions ◽  
Martensitic Transformation ◽  
Room Temperature ◽  
Fluorescent Protein ◽  
Martensitic Phase ◽  
Protein Crystal ◽  
High Tech ◽  
X Ray ◽  
Martensitic Phase Transition

Martensitic transformations are the first-order crystal-to-crystal phase transitions that occur mostly in materials such as steel, alloys and ceramics, thus having many technological applications. These phase transitions are rarely observed in molecular crystals and have not been detected in protein crystals. Reversibly switchable fluorescent proteins are widely used in biotechnology, including super-resolution molecular imaging, and hold promise as candidate biomaterials for future high-tech applications. Here, we report on a reversibly switchable fluorescent protein, Tetdron, whose crystals undergo a photo-induced martensitic transformation at room temperature. Room-temperature X-ray crystallography demonstrates that at equilibrium Tetdron chromophores are all in the trans configuration, with an ∼1:1 mixture of their protonated and deprotonated forms. Irradiation of a Tetdron crystal with 400 nm light induces a martensitic transformation, which results in Tetdron tetramerization at room temperature revealed by X-ray photocrystallography. Crystal and solution spectroscopic measurements provide evidence that the photo-induced martensitic phase transition is coupled with the chromophore deprotonation, but no trans–cis isomerization is detected in the structure of an irradiated crystal. It is hypothesized that protein dynamics assists in the light-induced proton transfer from the chromophore to the bulk solvent and in the ensuing martensitic phase transition. The unique properties of Tetdron may be useful in developing novel biomaterials for optogenetics, data storage and nanotechnology.

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