scholarly journals Modification of Double Oxide Film Defects with the Addition of Mo to An Al-Si-Mg Alloy

2021 ◽  
Author(s):  
Qi Chen ◽  
W. D. Griffiths
Keyword(s):  
Liquid Metal ◽  
Oxide Film ◽  
Cross Sections ◽  
Focused Ion Beam ◽  
Spinel Phase ◽  
Ion Beam ◽  
Transmission Electron Microscopy Analysis ◽  
Double Oxide ◽  
Alloy Castings ◽  
Film Defect

AbstractIn this work, Mo was added into Al melt to reduce the detrimental effect of double-oxide film defect. An air bubble was trapped in a liquid metal (2L99), served as an analogy for double-oxide film defect in aluminum alloy castings. It was found that the addition of Mo significantly accelerated the consumption of the entrapped bubble by 60 pct after holding for 1 hour. 2 sets of testbar molds were then cast, with 2L99 and 2L99+Mo alloy, with a badly designed running system, intended to deliberately introduce double oxide film defects into the liquid metal. Tensile testing showed that, with the addition of Mo, the Weibull modulus of the Ultimate Tensile Strength and pct Elongation was increased by a factor of 2.5 (from 9 to 23) and 2 (from 2.5 to 4.5), respectively. The fracture surface of 2L99+Mo alloy testbars revealed areas of nitrides contained within bi-film defects. Cross-sections through those defects by Focused Ion Beam milling suggested that the surface layer were permeable, which could be as thick as 30 μm, compared to around 500 nm for the typical oxide film thickness. Transmission Electron Microscopy analysis suggested that the nitride-containing layer consisted of nitride particles as well as spinel phase of various form. The hypothesis was raised that the permeability of the nitride layers promote the reaction between the entrapped atmosphere in the defect and the surrounding liquid metal, reducing the defect size and decreasing their impact on mechanical properties.

scholarly journals Double oxide film defects and the properties of aluminum castings. A review

2019 ◽  
pp. 5-12
Author(s):  
Mahmoud Ahmed El-Sayed
Keyword(s):  
Liquid Metal ◽  
Oxide Film ◽  
Aluminium Alloys ◽  
Oxide Films ◽  
Light Metal ◽  
Metal Alloy ◽  
Double Oxide ◽  
Factors Influencing ◽  
Aluminum Castings ◽  
Alloy Castings

Entrapped double oxide films are known to be the most detrimental defects in cast aluminium alloys. The research reported here was aimed at surveying the results of previous researches studying how these defects develop with time, with the intention of understanding their behaviour in the liquid metal once they have formed. This would give a better understanding of factors influencing the properties of light metal alloy castings which will lead to the development of improved practices by which healthier castings with reliable and more reproducible properties are obtained.

FIB Plan and Side View Cross-Sectional TEM Sample Preparation of Nanostructures

2013 ◽  
Vol 20 (1) ◽  
pp. 133-140 ◽  
Author(s):  
Filip Lenrick ◽  
Martin Ek ◽  
Daniel Jacobsson ◽  
Magnus T. Borgström ◽  
L. Reine Wallenberg
Keyword(s):  
Sample Preparation ◽  
Cross Sections ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Substrate Surface ◽  
Side View ◽  
Transmission Electron Microscopy Analysis ◽  
Cross Sectional ◽  
Transmission Electron ◽  
Electron Microscopy Analysis

AbstractFocused ion beam is a powerful method for cross-sectional transmission electron microscope sample preparation due to being site specific and not limited to certain materials. It has, however, been difficult to apply to many nanostructured materials as they are prone to damage due to extending from the surface. Here we show methods for focused ion beam sample preparation for transmission electron microscopy analysis of such materials, demonstrated on GaAs–GaInP core shell nanowires. We use polymer resin as support and protection and are able to produce cross-sections both perpendicular to and parallel with the substrate surface with minimal damage. Consequently, nanowires grown perpendicular to the substrates could be imaged both in plan and side view, including the nanowire–substrate interface in the latter case. Using the methods presented here we could analyze the faceting and homogeneity of hundreds of adjacent nanowires in a single lamella.

scholarly journals Modelling the temperature change of bifilm defects in Al cast alloys

2019 ◽  
pp. 13-17
Author(s):  
Mahmoud Ahmed El-Sayed
Keyword(s):  
Oxide Film ◽  
Fatigue Properties ◽  
Al Alloy ◽  
Heat Distribution ◽  
Cfd Model ◽  
Double Oxide ◽  
Cast Alloys ◽  
Alloy Castings ◽  
Film Defect ◽  
Surrounding Liquid

Double oxide films (bifilms) are significant defects in the casting of light alloys, and have been shown to decrease tensile and fatigue properties, and also increase their scatter, making casting properties unreproducible and unreliable. Recent research has suggested that the nature of oxide film defects may change with time, as the air inside the bifilm would react with the surrounding melt leading to its consumption, which may enhance the mechanical properties of Al alloy castings. It was suggested that in a pure Al melt, oxygen within the bifilm atmosphere would be consumed first to form alumina, then nitrogen would react to from AlN. A CFD model of the heat distribution associated with the reactions between the interior atmosphere of a double oxide film defect and the surrounding liquid alloy suggested that highly localized increases in temperature, up to 5000, could occur, over a scale of a few hundred micrometers. Such localized increases in temperature might lead to change the nature of the bifilm causing it to be less harmful to the properties of Al cast alloys.

An Study of Influence of Imperfections on the Delamination of Diamond-Like Carbon Films

2002 ◽  
Vol 719 ◽  
Author(s):  
Myoung-Woon Moon ◽  
Kyang-Ryel Lee ◽  
Jin-Won Chung ◽  
Kyu Hwan Oh
Keyword(s):  
Cross Sections ◽  
Focused Ion Beam ◽  
Imaging System ◽  
Ion Beam ◽  
Carbon Films ◽  
Diamond Like Carbon ◽  
Glass Substrates ◽  
Atomic Force ◽  
Initiation And Propagation

AbstractThe role of imperfections on the initiation and propagation of interface delaminations in compressed thin films has been analyzed using experiments with diamond-like carbon (DLC) films deposited onto glass substrates. The surface topologies and interface separations have been characterized by using the Atomic Force Microscope (AFM) and the Focused Ion Beam (FIB) imaging system. The lengths and amplitudes of numerous imperfections have been measured by AFM and the interface separations characterized on cross sections made with the FIB. Chemical analysis of several sites, performed using Auger Electron Spectroscopy (AES), has revealed the origin of the imperfections. The incidence of buckles has been correlated with the imperfection length.

FIB Enhancement of Mechanically Polished Cross-sections

2019 ◽  
Author(s):  
Becky Holdford
Keyword(s):  
Electron Microscope ◽  
High Resolution ◽  
Scanning Electron Microscope ◽  
Cross Sections ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
High Resolution Imaging ◽  
Chemical Attack ◽  
Resolution Imaging ◽  
Scanning Electron

Abstract On mechanically polished cross-sections, getting a surface adequate for high-resolution imaging is sometimes beyond the analyst’s ability, due to material smearing, chipping, polishing media chemical attack, etc.. A method has been developed to enable the focused ion beam (FIB) to re-face the section block and achieve a surface that can be imaged at high resolution in the scanning electron microscope (SEM).

Yield Enhancement Study: Process Variation and Design Margins Leading to Timing Issues in the RAM

2000 ◽  
Author(s):  
Srikanth Perungulam ◽  
Scott Wills ◽  
Greg Mekras
Keyword(s):  
Cross Sections ◽  
Digital Signal Processor ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Random Access ◽  
Digital Signal ◽  
Yield Enhancement ◽  
Final Conclusion ◽  
Stage Separation ◽  
Study Process

Abstract This paper illustrates a yield enhancement effort on a Digital Signal Processor (DSP) where random columns in the Static Random Access Memory (SRAM) were found to be failing. In this SRAM circuit, sense amps are designed with a two-stage separation and latch sequence. In the failing devices the bit line and bit_bar line were not separated far enough in voltage before latching got triggered. The design team determined that the sense amp was being turned on too quickly. The final conclusion was that a marginal sense amp design, combined with process deviations, would result in this type of failure. The possible process issues were narrowed to variations of via resistances on the bit and bit_bar lines. Scanning Electron Microscope (SEM) inspection of the the Focused Ion Beam (FIB) cross sections followed by Transmission Electron Microscopy (TEM) showed the presence of contaminants at the bottom of the vias causing resistance variations.

scholarly journals Is a Zirconia Dental Implant Safe When It Is Available on the Market?

Ceramics ◽  
2019 ◽  
Vol 2 (4) ◽  
pp. 568-577 ◽  
Author(s):  
Frigan ◽  
Chevalier ◽  
Zhang ◽  
Spies
Keyword(s):  
Phase Transformation ◽  
Dental Implants ◽  
Cross Sections ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Layer Growth ◽  
Transformation Toughening ◽  
High Fracture ◽  
Clinical Safety ◽  
Dynamic Fatigue

The market share of zirconia (ZrO2) dental implants is steadily increasing. This material comprises a polymorphous character with three temperature-dependent crystalline structures, namely monoclinic (m), tetragonal (t) and cubic (c) phases. Special attention is given to the tetragonal phase when maintained in a metastable state at room temperature. Metastable tetragonal grains allow for the beneficial phenomenon of Phase Transformation Toughening (PTT), resulting in a high fracture resistance, but may lead to an undesired surface transformation to the monoclinic phase in a humid environment (low-temperature degradation, LTD, often referred to as ‘ageing’). Today, the clinical safety of zirconia dental implants by means of long-term stability is being addressed by two international ISO standards. These standards impose different experimental setups concerning the dynamic fatigue resistance of the final product (ISO 14801) or the ageing behavior of a standardized sample (ISO 13356) separately. However, when evaluating zirconia dental implants pre-clinically, oral environmental conditions should be simulated to the extent possible by combining a hydrothermal treatment and dynamic fatigue. For failure analysis, phase transformation might be quantified by non-destructive techniques, such as X-Ray Diffraction (XRD) or Raman spectroscopy, whereas Scanning Electron Microscopy (SEM) of cross-sections or Focused Ion Beam (FIB) sections might be used for visualization of the monoclinic layer growth in depth. Finally, a minimum load should be defined for static loading to fracture. The purpose of this communication is to contribute to the current discussion on how to optimize the aforementioned standards in order to guarantee clinical safety for the patients.

scholarly journals In Situ Delineation Etch Reveals Subtle Detail in SEM Images of Ion Milled Cross Sections Enabling In-Fab 3-D Metrology and Characterization

2000 ◽  
Vol 8 (2) ◽  
pp. 36-39
Author(s):  
Clive Chandler
Keyword(s):  
Sample Preparation ◽  
Cross Sections ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Automated System ◽  
Sem Images ◽  
Difficult Time ◽  
Device Structures ◽  
Wet Etch ◽  
Conventional Sample

Control of layer thickness is critically important in the manufacture of semiconductor devices. Cross-sectioning exposes device structures for direct examination but conventional sample preparation procedures are difficult, time consuming, and grossly destructive. Cross sections created by focused ion beam (FIB) milling are easier, faster, and less destructive but have not offered the clear layer delineation provided by etching in the conventional sample preparation process. A new gas etch capability (Delineation Etch™ from FEI Company) offers results that are equivalent to conventional wet-etch preparations in a fraction of the time from a single, automated system in the fab without destroying the wafer. The new etch process also has application in milling high-aspect-ratio holes to create contacts to buried metal layers, and in deprocessing devices to reveal silicon and polysilicon structures.

Alternative FIB TEM Sample Preparation Method for Cross-Sections of Thin Metal Films Deposited on Polymer Substrates

2013 ◽  
Vol 19 (4) ◽  
pp. 1080-1091 ◽  
Author(s):  
Felipe Rivera ◽  
Robert Davis ◽  
Richard Vanfleet
Keyword(s):  
Sample Preparation ◽  
Cross Sections ◽  
Elemental Analysis ◽  
Focused Ion Beam ◽  
Preparation Method ◽  
Ion Beam ◽  
Sample Preparation Method ◽  
Site Specific ◽  
Polymer Substrates ◽  
Interface Layers

AbstractTransmission electron microscopy (TEM) and focused ion beam (FIB) are proven tools to produce site-specific samples in which to study devices from initial processing to causes for failure, as well as investigating the quality, defects, interface layers, etc. However, the use of polymer substrates presents new challenges, in the preparation of suitable site-specific TEM samples, which include sample warping, heating, charging, and melting. In addition to current options that address some of these problems such as cryo FIB, we add an alternative method and FIB sample geometry that address these challenges and produce viable samples suitable for TEM elemental analysis. The key feature to this approach is a larger than usual lift-out block into which small viewing windows are thinned. Significant largely unthinned regions of the block are left between and at the base of the thinned windows. These large unthinned regions supply structural support and thermal reservoirs during the thinning process. As proof-of-concept of this sample preparation method, we also present TEM elemental analysis of various thin metallic films deposited on patterned polycarbonate, lacquer, and poly-di-methyl-siloxane substrates where the pattern (from low- to high-aspect ratio) is preserved.

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