Modelling diffusion in crystals under high internal stress gradients

SU-8 photoresist has received a lot of attention in the MEMS field because of its excellent lithography properties. However, its high internal stress affects the overall pattern quality of the micro structures. The purpose of this work is to reduce the internal stress in SU-8 micro structure by ultrasonic stress relief technology. The stress relief mechanism of SU-8 micro structure was presented. The effect of ultrasonic stress relief on SU-8 micro structure was studied by experiments. The experimental results show that the internal stress in SU-8 micro structures can be reduced by ultrasonic stress relief technology.

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Deformation Behavior And Internal Stress Of Icosahedral Al-Pd-Mn With Decagonal Phase Lamellae At Elevated Temperatures

MRS Proceedings ◽

10.1557/proc-553-331 ◽

1998 ◽

Vol 553 ◽

Author(s):

H. Hirai ◽

T. Tomita ◽

F. Yoshida ◽

H. Nakashima

Keyword(s):

Stress Relaxation ◽

Strain Rate ◽

Internal Stress ◽

Stress Exponent ◽

Deformation Behavior ◽

Elevated Temperatures ◽

Initial Strain Rate ◽

Decagonal Phase ◽

Thermally Activated ◽

High Internal Stress

AbstractFine decagonal phase lamellae-bearing icosahedral Al-Pd-Mn quasicrystals were tested compressionally at temperatures of 997 to 1073 K and initial strain rate of 3 × 10−5. to I × 10−4 S−1, and stress relaxation tests were performed at various stages of deformation. The results confirmed the thermally activated nature of deformation, and the stress exponent of strain rate was around 4. Internal stress for deformation estimated by Kikuchi's method reached 50 to 90 % of applied stress. The effective stress exponent of strain rate was revealed to be about 1.3. At least a part of high internal stress was attributable to complicated dislocation microstructure.

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Mechanical Properties of Magnesium Alloys Produced by the Heated Mold Continuous Casting Process

Archives of Foundry Engineering ◽

10.1515/afe-2016-0111 ◽

2016 ◽

Vol 16 (4) ◽

pp. 208-216

Author(s):

M. Okayasu ◽

S. Wu ◽

T. Tanimoto ◽

S. Takeuchi

Keyword(s):

Mechanical Properties ◽

Continuous Casting ◽

Internal Stress ◽

Magnesium Alloys ◽

Casting Process ◽

Fatigue Properties ◽

Continuous Casting Process ◽

Etching Technique ◽

Micro Cracks ◽

High Internal Stress

Abstract Investigation of the tensile and fatigue properties of cast magnesium alloys, created by the heated mold continuous casting process (HMC), was conducted. The mechanical properties of the Mg-HMC alloys were overall higher than those for the Mg alloys, made by the conventional gravity casting process (GC), and especially excellent mechanical properties were obtained for the Mg97Y2Zn1-HMC alloy. This was because of the fine-grained structure composed of the α-Mg phases with the interdendritic LPSO phase. Such mechanical properties were similar levels to those for conventional cast aluminum alloy (Al84.7Si10.5Cu2.5Fe1.3Zn1 alloys: ADC12), made by the GC process. Moreover, the tensile properties (σUTS and εf) and fatigue properties of the Mg97Y2Zn1-HMC alloy were about 1.5 times higher than that for the commercial Mg90Al9Zn1-GC alloy (AZ91). The high correlation rate between tensile properties and fatigue strength (endurance limit: σl) was obtained. With newly proposed etching technique, the residual stress in the Mg97Y2Zn1 alloy could be revealed, and it appeared that the high internal stress was severely accumulated in and around the long-period stacking-order phases (LPSO). This was made during the solidification process due to the different shrinkage rate between α-Mg and LPSO. In this etching technique, micro-cracks were observed on the sample surface, and amount of micro-cracks (density) could be a parameter to determine the severity of the internal stress, i.e., a large amount to micro-cracks is caused by the high internal stress.

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Effect of current density on the deposit stress in gold electroplating

Modern Physics Letters B ◽

10.1142/s0217984917501883 ◽

2017 ◽

Vol 31 (17) ◽

pp. 1750188

Author(s):

Shuangyue Hou ◽

Ying Xiong ◽

Shan Chen ◽

Xiangyu Chen ◽

Penghui Xiong ◽

...

Keyword(s):

Internal Stress ◽

Current Density ◽

Substrate Material ◽

Gold Deposits ◽

X Ray Diffraction ◽

Contrast Imaging ◽

X Ray ◽

Critical Issues ◽

Surface Morphologies ◽

High Internal Stress

As the key components of grating-based X-ray phase contrast imaging, absorption gratings are essential to be fabricated. In fact, the internal stress is one of the critical issues for the application of the electroplated gold deposit as the absorption metal for absorption gratings. It is common that high internal stress levels can cause the deposit cracking, blistering and peeling away from the substrate material. This study investigates the effect of current density on the internal stress by the bent strip method. The surface morphologies of gold deposits are examined using scanning electron microscopy (SEM) and the crystal structure of the electroplated deposit is analyzed by X-ray diffraction (XRD). The change of current density reverses the internal stress of the deposits from compressive to tensile. The value of deposit stress can be near zero by optimizing the current density.

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Point Defect Production Under High Internal Stress Without Dislocations in Ni and Cu

Radiation Effects and Defects in Solids ◽

10.1080/10420150211403 ◽

2002 ◽

Vol 157 (1-2) ◽

pp. 171-178 ◽

Cited By ~ 21

Author(s):

K. Sato ◽

T. Yoshiie ◽

Y. Satoh ◽

Q. Xu ◽

E. Kuramoto ◽

...

Keyword(s):

Point Defect ◽

Internal Stress ◽

Defect Production ◽

High Internal Stress

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A Study on the Hydrogen Evolving Activity of Electroplated Ni-P Coating by Using the Taguchi Method

Journal of New Materials for Electrochemical Systems ◽

10.14447/jnmes.v14i4.96 ◽

2011 ◽

Vol 14 (4) ◽

pp. 237-245 ◽

Cited By ~ 2

Author(s):

Hung-Bin Lee ◽

Chen-Hsiung Hsu ◽

Dong-Sing Wuu

Keyword(s):

Grain Size ◽

Internal Stress ◽

Process Parameters ◽

Current Density ◽

Duty Cycle ◽

Phosphorous Acid ◽

Taguchi’S Method ◽

P Content ◽

The One ◽

High Internal Stress

The optimal catalytic activity of the electrodeposited Ni-P coating with the control of the process parameters was performed in this study by using Taguchi’s method. The controlled process parameters included current density, duty cycle and the concentration of the phosphorous acid in the electrolyte. The correlation among the controlled parameters and the resulted hydrogen evolution reaction (HER) activity was discussed with emphasis on the influence of the P content, internal stress, roughness and grain size of the coating. The optimal HER property was obtained for the electrodeposition of Ni-P coating with a phosphorous acid concentration of 5g/l, current density of 16A/dm2 and duty cycle of 100 %. The resulted Ni-P coating with a better HER property was the one with P content 3at%, an internal stress higher than 10MPa, grain size 10~15nm and surface roughness higher than 100nm. In addition, the cracking of the coating due to high internal stress favored the raise of the HER activity.

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Study on Internal Stress in Micro-Electroformed Layer

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.645-646.178 ◽

2015 ◽

Vol 645-646 ◽

pp. 178-183 ◽

Cited By ~ 3

Author(s):

Li Qun Du ◽

Zhi Cheng Tan ◽

Chang Song ◽

Zhong Zhao ◽

Qing Feng Li ◽

...

Keyword(s):

Internal Stress ◽

Compressive Stress ◽

Current Density ◽

Stress Reduction ◽

Research Work ◽

Ultrasonic Power ◽

Free Solution ◽

And Performance ◽

Additive Solution ◽

High Internal Stress

Micro electroforming technology is widely used in fabrication of multilayer or moveable metal micro devices. The fabrication of these devices is usually suffered from high internal stress in micro-electroformed layers which seriously restricts the application and development of micro electroforming technology. Therefore, to control the internal stress is very important for improving the quality and performance of micro-electroformed layer. However, published studies on internal stress in the electroforming layer were mostly based on additive-free solution. According to additive solution, the effect of ultrasonic and current density on compressive stress occurring in the electroforming layer is investigated in this paper. The results indicate that the compressive stress keeps increasing with current density within range from 0.2 to 2 A/dm2. Meanwhile, the compressive stress in ultrasonic solution decreases by 73.4 MPa averagely comparing to that in ultrasonic-free solution, and the compressive stress also keeps decreasing with the ultrasonic power which gets the lowest value at 200W. Moreover, the mechanisms of additive-induced compressive stress and ultrasonic relieving compressive stress are discussed. This research work will complement the ultrasonic-stress reduction theory and may contribute to the development of micro electroforming technology.

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Molecular Hydrogen in Amorphous Silicon with High Internal Stress

Japanese Journal of Applied Physics ◽

10.1143/jjap.46.5050 ◽

2007 ◽

Vol 46 (8A) ◽

pp. 5050-5052 ◽

Cited By ~ 1

Author(s):

Parvaneh Danesh ◽

Blagoy Pantchev ◽

Bernd Schmidt ◽

Dieter Grambole

Keyword(s):

Amorphous Silicon ◽

Internal Stress ◽

Molecular Hydrogen ◽

High Internal Stress

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On the Propagation of Twin-Fault-Induced Stress in Platelet Fau-Framework Zeolites

MRS Proceedings ◽

10.1557/proc-111-177 ◽

1987 ◽

Vol 111 ◽

Cited By ~ 7

Author(s):

M. M. J. Treacy ◽

J. M. Newsam ◽

D. E. W. Vaughan ◽

R. A. Beyerlein ◽

S. B. Rice ◽

...

Keyword(s):

Internal Stress ◽

Fault Zone ◽

Stress Gradients ◽

Induced Stress ◽

Twin Fault ◽

Rhombohedral Distortion

AbstractA model describing the propagation of a rhombohedral distortion in platelet CSZ–1 zeolites is presented. It is proposed that internal stress gradients grown into CSZ–1 platelets at synthesis are responsible for this distortion of the cubic FAU framework, where the spacings of 111 planes parallel to the platelet surfaces are elongated relative to the {111} planes. The presence of inhomogeneities is suggested by the presence of thin bands of twin faults which are invariably observed near the central layers of each platelet. Elastic modelling confirms that the effects of any stress associated with such twin faults will be most pronounced in the thinnest platelets, where the effects of elastic relaxation are minimal, and where the width of the fault zone relative to the platelet thickness is maximal. Platelet CSZ–3 and Y-type zeolites, which are considerably thicker, are therefore not expected to show significant rhombohedral distortion despite the presence of similar twin fault bands.

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