scholarly journals Characterization and Prediction of Texture in Laser Annealed NiTi Shape Memory Thin Films

2010 ◽  
Author(s):  
Gen Satoh ◽  
Y. Lawrence Yao ◽  
Xu Huang ◽  
Ainissa Ramirez
Keyword(s):  
Thin Film ◽  
Monte Carlo ◽  
Shape Memory ◽  
Grain Growth ◽  
Electron Backscatter Diffraction ◽  
Laser Crystallization ◽  
3 Dimensional ◽  
Shape Memory Properties ◽  
Melting Regime ◽  
Grain Growth Model

Thin film shape memory alloys are a promising material for use in micro-scale devices for actuation and sensing due to their strong actuating force, substantial displacements, and large surface to volume ratios. NiTi, in particular, has been of great interest due to its biocompatibility and corrosion resistance. Effort has been directed toward adjusting the microstructure of as-deposited films in order to modify their shape memory properties for specific applications. The anisotropy of the shape memory and superelastic effects suggests that inducing preferred orientations could allow for optimization of shape memory properties. Limited work, however, has been performed on adjusting the crystallographic texture of these films. In this study, thin film NiTi samples are processed using excimer laser crystallization and the effect on the overall preferred orientation is analyzed through the use of electron backscatter diffraction and x-ray diffraction. A 3-dimensional Monte Carlo grain growth model is developed to characterize textures formed through surface energy induced abnormal grain growth during solidification. Furthermore, a scaling factor between Monte Carlo steps and real time is determined to aid in the prediction of texture changes during laser crystallization in the partial melting regime.

scholarly journals Characterization and Prediction of Texture in Laser Annealed NiTi Shape Memory Thin Films

2012 ◽  
Vol 134 (5) ◽  
Author(s):  
Gen Satoh ◽  
Xu Huang ◽  
Ainissa G. Ramirez ◽  
Y. Lawrence Yao
Keyword(s):  
Thin Film ◽  
Monte Carlo ◽  
Shape Memory ◽  
Grain Growth ◽  
Electron Backscatter Diffraction ◽  
Three Dimensional ◽  
Laser Crystallization ◽  
Shape Memory Properties ◽  
Melting Regime ◽  
Grain Growth Model

Thin film shape memory alloys are a promising material for use in microscale devices for actuation and sensing due to their strong actuating force, substantial displacements, and large surface to volume ratios. NiTi, in particular, has been of great interest due to its biocompatibility and corrosion resistance. Effort has been directed toward adjusting the microstructure of as-deposited films in order to modify their shape memory properties for specific applications. The anisotropy of the shape memory and superelastic effects suggests that inducing preferred orientations could allow for optimization of shape memory properties. Limited work, however, has been performed on adjusting the crystallographic texture of these films. In this study, thin film NiTi samples are processed using excimer laser crystallization and the effect on the overall preferred orientation is analyzed through the use of electron backscatter diffraction and X-ray diffraction. A three-dimensional Monte Carlo grain growth model is developed to characterize textures formed though surface energy induced abnormal grain growth during solidification. Furthermore, a scaling factor between Monte Carlo steps and real time is determined to aid in the prediction of texture changes during laser crystallization in the partial melting regime.

Three-dimensional monte-carlo simulation of grain growth in Pt-Co thin film

2002 ◽  
Vol 31 (10) ◽  
pp. 965-971 ◽  
Author(s):  
Sung Il Park ◽  
Sang Soo Han ◽  
Hyoung Gyu Kim ◽  
Joong Keun Park ◽  
Hyuck Mo Lee
Keyword(s):  
Thin Film ◽  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Grain Growth ◽  
Three Dimensional

Effect of the Intercalation of the Carbon Layer on the Kinetics of Grain Growth of FePt Magnetic Thin Film during Ordering Reaction - A Monte Carlo Simulation Study

2007 ◽  
Vol 558-559 ◽  
pp. 1237-1242
Author(s):  
M.C. Kim ◽  
D.A. Kim ◽  
Joong Kuen Park
Keyword(s):  
Thin Film ◽  
Monte Carlo Simulation ◽  
Grain Size ◽  
Monte Carlo ◽  
Grain Growth ◽  
Carbon Layer ◽  
Carbon Addition ◽  
Monte Carlo Simulation Study ◽  
Ordering Kinetics ◽  
Kinetics Of

The effect of carbon addition on the grain growth and ordering kinetics of FePt film has been experimentally studied by sputter-depositing a monolithic FePt-20at.%C film of 24 nm. Carbon addition of 20at.% to FePt thin film in a form of FePt (20 nm)/Cn (4 nm) (n = 1, 4) significantly reduced both the grain growth and ordering kinetics. Reducing the thickness of carbon layer, i.e. from n = 1 to n = 4, led to a much finer grain size distribution as well as to a finer grain size. The Monte Carlo simulation study indicated that the decrease of grain growth and ordering kinetics is primarily due to a continuous decrease of the mobility of order – disorder inter-phase with the progress of ordering reaction. This can eventually lead to a stable 2-phase grain structure inter-locked by low mobility inter-phases and is responsible for the formation of a fine grain size distribution in the FePt/Cn film with n = 4.

A Study of Self-Reinforcement Phenomenon in Silicon Nitride by Monte-Carlo Simulation

1998 ◽  
Vol 529 ◽  
Author(s):  
Y. Okamoto ◽  
N. Hirosaki ◽  
H. Matsubara
Keyword(s):  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Silicon Nitride ◽  
Liquid Phase ◽  
Grain Growth ◽  
Potts Model ◽  
Dominant Factor ◽  
Microstructure Development ◽  
Principal Characteristics ◽  
Grain Growth Model

AbstractA grain growth model based on the results of Monte-Carlo simulations is proposed for silicon nitride. The model was derived from the Potts model; in addition, principal characteristics of silicon nitride such as presence of liquid phase and anisotropy of grain growth were introduced. Employing this model, microstructure development of silicon nitride was investigated.Under certain simulation conditions, several grains grew in preference to other grains, and consequently, a self-reinforced microstructure was produced similar to that of actual silicon nitride. In particular, liquid phase fraction was found to be dominant factor affecting microstructure development.

Abnormal Subgrain Growth by Monte Carlo Simulation Based on Hot-Rolled AA5005 Aluminum Alloy Texture

2007 ◽  
Vol 558-559 ◽  
pp. 377-382 ◽  
Author(s):  
Sheng Yu Wang ◽  
Anthony D. Rollett
Keyword(s):  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Aluminum Alloy ◽  
Grain Growth ◽  
Electron Backscatter Diffraction ◽  
Subgrain Structure ◽  
Digital Representations ◽  
Subgrain Growth ◽  
Rolled Aluminum ◽  
Hot Rolled

The subgrain structure of hot rolled aluminum alloy AA 5005 has been characterized on as-received samples using Electron Backscatter Diffraction (EBSD). Based on the OIM scans of RD-ND and TD-ND, 3 dimensional microstructures of subgrains are built up using the 3D Microstructure Builder, which is a method for developing statistically representative digital representations of microstructures. Following the generation of microstructure, different textures were fit to these reconstructed 3D microstructures, based on individual components such as Brass and S textures. For this study, the Brass texture was chosen as an exemplary case. Monte Carlo simulation was used to model subgrain coarsening and visualization was a key to detecting abnormal grain growth. The main objective is to understand the circumstances under which we can expect abnormal (sub-)grain growth to lead to nucleation of recrystallization.

scholarly journals Melt-mediated laser crystallization of thin film NiTi shape memory alloys

2007 ◽  
Author(s):  
Andrew J. Birnbaum ◽  
Ui-Jin Chung ◽  
Xu Huang ◽  
Ainissa G. Ramirez ◽  
Sean Polvino ◽  
...  
Keyword(s):  
Thin Film ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Laser Crystallization ◽  
Niti Shape Memory Alloys

Determination of Stoichiometry of GaAs Component in (Gaas)Ge Epitaxially Grown Thin Films by Electron Microprobe X-Ray Analysis

1990 ◽  
Vol 48 (2) ◽  
pp. 264-265
Author(s):  
D. R. Liu ◽  
S. S. Shinozaki ◽  
R. J. Baird
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Compound Semiconductors ◽  
Energy Dispersive Analysis ◽  
X Ray ◽  
Metastable Alloys ◽  
Lower Voltage

The epitaxially grown (GaAs)Ge thin film has been arousing much interest because it is one of metastable alloys of III-V compound semiconductors with germanium and a possible candidate in optoelectronic applications. It is important to be able to accurately determine the composition of the film, particularly whether or not the GaAs component is in stoichiometry, but x-ray energy dispersive analysis (EDS) cannot meet this need. The thickness of the film is usually about 0.5-1.5 μm. If Kα peaks are used for quantification, the accelerating voltage must be more than 10 kV in order for these peaks to be excited. Under this voltage, the generation depth of x-ray photons approaches 1 μm, as evidenced by a Monte Carlo simulation and actual x-ray intensity measurement as discussed below. If a lower voltage is used to reduce the generation depth, their L peaks have to be used. But these L peaks actually are merged as one big hump simply because the atomic numbers of these three elements are relatively small and close together, and the EDS energy resolution is limited.

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