Comparison of Oxide Thickness of Aluminium and the Effects of Selected Alloying Additions

2013 ◽  
Vol 765 ◽  
pp. 180-184 ◽  
Author(s):  
Elizabeth M. Hinton ◽  
William D. Griffiths ◽  
Nick R. Green
Keyword(s):  
Oxide Thickness ◽  
The Other ◽  
Mg Alloy ◽  
Oxide Growth ◽  
Alloying Additions ◽  
Fe Alloys ◽  
Holding Temperature

An experiment was undertaken to study the oxidation of liquid superpure aluminium (SP-Al) and alloys containing Mg, Si, Cu and Fe. The alloys were held at 750 °C, for a number of different holding times up to 7 hours. A comparison of the oxidation of SP-Al (superpure) held at 700 °C, 750 °C and 800 °C for 3 hours was also carried out. On observation of the samples using SEM and EDX the oxides of SP-Al and the Al-Mg alloy grew quickly (by 5.8 μm after 7 hours and 2 μm after 1 hour, respectively), in a manner reported in the literature. The other alloys had reduced rates of oxide growth, with thickness changes between 30 nm and 0.25 μm for Al-Si, Al-Cu and Al‑Fe alloys. Changes in holding temperature showed a thick oxide on samples held at 850 °C for 3 hours.

scholarly journals Effect of combined metal-carbon additions on the microstructure and structure of Sm2Fe17

2003 ◽  
Vol 18 (2) ◽  
pp. 279-283 ◽  
Author(s):  
B.E. Meacham ◽  
J.E. Shield
Keyword(s):  
Solute Drag ◽  
Type Structure ◽  
Drag Effect ◽  
Microstructural Refinement ◽  
Atomic Size ◽  
Alloying Additions ◽  
Grain Structures ◽  
Fe Alloys ◽  
Rapidly Solidified ◽  
Carbon Additions

The effect of combined alloying additions on the structure and scale of rapidly solidified Sm–Fe alloys was investigated. Transition metal additions tend to promote the formation of the disordered TbCu7-type structure in Sm2Fe17 alloys, as determined by monitoring the long-range order parameter. Essentially no order was observed for M = Ti, Zr, V, or Nb. Thus, the structure was close to the prototypical TbCu7-type structure. With M = Si, a large amount of order was observed (S = 0.62), resulting in a structure closer to the well-ordered Th2Zn17-type. The microstructural scale was also affected by alloying. In this case, refinement depended on the substituent and also on carbon for microstructural refinement. The scale of the as-solidified grain structures ranged from 100 nm for SiC-modified alloys to 13 nm for NbC-modified alloys. The degree of refinement was directly related to the atomic size of the M addition. The refinement was the result of solute partitioning to grain boundaries, resulting in a solute drag effect that lowered the growth rates.

STRADDLE-GATE TRANSISTOR: A MOSFET IN THE LIMIT OF USEFUL FIELD-EFFECT

2000 ◽  
Vol 10 (01) ◽  
pp. 231-245 ◽  
Author(s):  
SANDIP TIWARI ◽  
A. KUMAR ◽  
J. J. WELSER
Keyword(s):  
Field Effect ◽  
Field Effect Transistor ◽  
Oxide Thickness ◽  
Error Rates ◽  
Soft Error ◽  
The Other ◽  
Power Gain ◽  
Virtual Source ◽  
Effect Transistor ◽  
Output Conductance

For transistor, the limit of usable field-effect is defined by tunneling between the source and the drain - the mechanism that competes with field-effect as device dimensions shrink to near deBroglie wavelength. This is a more fundamental constraint in the operation of a field-effect transistor than random dopants, oxide thickness, doping magnitudes and depth, gate resistivity, soft-error rates, etc. We describe here a MOSFET structure, the straddle-gate transistor, that uses inversion regions as virtual source and drain, operates within the limits placed by the other constraints, and operates at acceptable power levels with good power gain and output conductance at 10 nm channel lenth. Experimental behavior of the straddle geometry are also described to summarized the advantages accrued using electron injection from the thin inversion regions.

The Effect of Dopant Concentration on the Native Oxide Growth on Silicon Wafer Surface

1992 ◽  
Vol 259 ◽  
Author(s):  
Y. Ishimaru ◽  
M. Yoshiki ◽  
T. Hatanaka
Keyword(s):  
Silicon Wafer ◽  
Silicon Surface ◽  
Dopant Concentration ◽  
Oxide Thickness ◽  
Native Oxide ◽  
Wafer Surface ◽  
Oxide Growth ◽  
X Ray ◽  
Silicon Bulk ◽  
P Type

ABSTRACTThe effects of dopant type and dopant concentration on the native oxide growth in air on the silicon surface were investigated. The oxide thickness was measured by X-ray photoelectron spectrometry (XPS). The oxide was thicker on n-type Si than on p-type Si in early oxidation. The oxide increased linearly with the dopant concentration. This enhancement of oxidation was assumed to be caused by vacancies near the surface in the silicon bulk.

Key Microstructural Features Responsible for Improved Stress Corrosion Cracking Resistance and Weldability in 7xxx Series Al Alloys Containing Micro / Trace Alloying Additions

2006 ◽  
Vol 519-521 ◽  
pp. 315-320 ◽  
Author(s):  
A.K. Mukhopadhyay ◽  
K. Satya Prasad ◽  
Vikas Kumar ◽  
G. Madhusudhan Reddy ◽  
S.V. Kamat ◽  
...  
Keyword(s):  
Quantitative Data ◽  
Microstructural Analysis ◽  
High Strength ◽  
Al Alloys ◽  
The Other ◽  
Alloying Additions ◽  
Cu Alloys ◽  
Medium Strength ◽  
Retrogression And Reaging ◽  
Peak Aged

The commercial 7xxx series Al alloys are based on medium strength Al-Zn-Mg and high strength Al-Zn-Mg-Cu systems. The medium strength alloys are weldable, whilst the high strength alloys are nonweldable. On the other hand, the Cu-free, weldable alloys suffer from poor SCC resistance. It is the purpose of this article to provide quantitative data and microstructural analysis to demonstrate that small additions of either Ag or Sc to Al-Zn-Mg and Al-Zn-Mg-Cu alloys bring about very significant improvement in SCC resistance and weldability, respectively. The improvement in SCC resistance of the Cu-bearing alloys due to over aging and retrogression and reaging (RRA) is further discussed in light of a similar improvement in the SCC resistance of these alloys, when peak aged, due to Ag and Sc additions.

A mechanistic model for oxide growth and dissolution during corrosion of Cr-containing alloys

2015 ◽  
Vol 180 ◽  
pp. 113-135 ◽  
Author(s):  
M. Momeni ◽  
J. C. Wren
Keyword(s):  
Metal Oxide ◽  
Oxide Layer ◽  
Metal Cation ◽  
Corrosion Behaviour ◽  
Mechanistic Model ◽  
Potential Drop ◽  
Oxide Thickness ◽  
Oxide Growth ◽  
Metal Oxidation ◽  
Charge Balance

We have developed a corrosion model that can predict metal oxide growth and dissolution rates as a function of time for a range of solution conditions. Our model considers electrochemical reactions at the metal/oxide and oxide/solution interfaces, and the metal cation flux from the metal to the solution phase through a growing oxide layer, and formulates the key processes using classical chemical reaction rate or flux equations. The model imposes mass and charge balance and hence, is labeled as the Mass Charge Balance (MCB) model. Mass and charge balance dictate that at any given time the oxidation (or metal cation) flux must be equal to the sum of the oxide growth flux and the dissolution flux. For each redox reaction leading to the formation of a specific oxide, the metal oxidation flux is formulated using a modified Butler–Volmer equation with an oxide-thickness-dependent effective overpotential. The oxide growth and dissolution fluxes have a first-order dependence on the metal cation flux. The rate constant for oxide formation also follows an Arrhenius dependence on the potential drop across the oxide layer and hence decreases exponentially with oxide thickness. This model is able to predict the time-dependent potentiostatic corrosion behaviour of both pure iron, and Co–Cr and Fe–Ni–Cr alloys.

In Situ Spectroscopic Ellipsometry Study of SiC Oxidation at Low Oxygen-Partial-Pressures

2010 ◽  
Vol 645-648 ◽  
pp. 813-816 ◽  
Author(s):  
Keiko Kouda ◽  
Yasuto Hijikata ◽  
Hiroyuki Yaguchi ◽  
Sadafumi Yoshida
Keyword(s):  
Growth Rate ◽  
Spectroscopic Ellipsometry ◽  
Reaction Rate ◽  
Oxidation Process ◽  
Early Stage ◽  
Oxide Thickness ◽  
Oxide Growth ◽  
Low Oxygen ◽  
Partial Pressures

We have investigated the oxidation process of SiC (000-1) C-face at low oxygen partial pressures using an in-situ spectroscopic ellipsometry. The oxide growth rate decreased steeply at the early stage of oxidation and then slowly decreased with increasing oxide thickness. The initial oxide growth rate was almost proportional to the oxygen　partial　pressure for both the polar directions. This result suggests that the initial interfacial reaction rate is constant regardless of the concentration of oxidants reaching the interface.

Effect of Nd on Microstructures and Properties of AZ31 Wrought Mg Alloy

2007 ◽  
Vol 546-549 ◽  
pp. 301-304
Author(s):  
Wei Qiu ◽  
En Hou Han ◽  
Lu Liu
Keyword(s):  
Mechanical Properties ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Mg Alloys ◽  
The Other ◽  
Mg Alloy ◽  
X Ray Diffraction ◽  
X Ray ◽  
Microstructures And Mechanical Properties ◽  
Re Elements

Addition of RE elements to Al-containing Mg alloys can improve properties of Mg alloys at elevated temperatures. In the present investigation, hot-extruded AZ31+x%Nd. (x=0.1,0.3,0.6and1.0 wt%) wrought Mg alloy were prepared .The effects of Nd on microstructures and mechanical properties at room temperature of new alloy were investigated. The investigation found that Nd can bring about two kind of precipitation phases . One is AlNd phase, the other is AlNdMn phase, which were identified as Al11Nd3 and Al8NdMn4 by X-ray diffraction and TEM.

Modelling of Corrosion Induced Stresses during Zircaloy-4 Oxidation in Air

2008 ◽  
Vol 595-598 ◽  
pp. 419-427 ◽  
Author(s):  
Vincent Busser ◽  
Jean Desquines ◽  
Stéphanie Fouquet ◽  
Marie Christine Baietto ◽  
Jean Paul Mardon
Keyword(s):  
Oxide Layer ◽  
Research Work ◽  
Oxide Thickness ◽  
Stress Profile ◽  
Oxide Growth ◽  
Large Set ◽  
Transient Experiments ◽  
Cracking Mechanisms ◽  
Oxidation In Air ◽  
Good Agreement

In the frame of its research work on nuclear fuel safety, the French “Institut de Radioprotection et de Sûreté Nucléaire” (IRSN) has highlighted the importance of cladding tube oxidation on its thermomechanical behavior. The occurrence of radial cracking and spallation has been observed as the main mechanisms for the zirconia layer degradation during transient experiments. A study of these two mechanisms has been jointly launched by IRSN and Areva-NP. Thus laboratory air oxidations of fully recrystallized or stress-relieved low-tin Zircaloy-4 cladding tubes have been performed. Representative oxide layer thicknesses varying from 10 to 100 0m have been obtained. SEM micrographs of the obtained oxidised samples show that short circumferential cracks are periodically distributed in the oxide thickness. For specimens with oxide film thickness greater than 30 0m, radial cracks are initiated from the outer surface of the oxide layer and propagated radially. Veins characterised by the lack of circumferentially orientated crack are evidenced. All these phenomena are mainly linked to high compressive stress levels in the zirconia layer. A model describing the stress evolution in the oxide and in the cladding has been developed. This model takes into account the influence of elasticity, cladding creep, oxide growth and thermal expansion. Deflection tests data [15] are used to calibrate the oxide growth modelling. The model enables the evaluation of strain or stress profile in the oxide layer and in the base metal. Numerical results are in good agreement with a large set of axial and circumferential strains measurements. Further a better understanding of cracking mechanisms is achieved considering the good agreement between experimental and numerical analysis.

scholarly journals Wire-arc additive manufacturing of Al-Mg alloy using CMT and PMC technologies

2018 ◽  
Vol 233 ◽  
pp. 00031 ◽  
Author(s):  
Bianca F. Gomes ◽  
Paulo J. Morais ◽  
Vítor Ferreira ◽  
Margarida Pinto ◽  
Luiz H. de Almeida
Keyword(s):  
Mechanical Properties ◽  
Additive Manufacturing ◽  
Raw Materials ◽  
Industrial Applications ◽  
The Other ◽  
Mg Alloy ◽  
Cold Metal Transfer ◽  
Small Pore ◽  
Wire Arc Additive Manufacturing ◽  
Pore Fraction

Among the several metallic additive manufacturing (MAM) technologies available, the wire-and-arc based ones are very beneficial due to the lower operational costs, higher efficiency use of raw materials, and high deposition rates achieved. The Cold Metal Transfer (CMT) process stands out by the lower heat input compared to the other wire-and-arc based methods. On the other hand, processes such as Pulse Multi Control (PMC) and its variants have not been tested yet in additive manufacturing and for this reason they should be evaluated. Therefore, considering the technologies potential and the need of automotive and aeronautical industry of manufacturing parts of complex and optimized geometry in a faster way, the study of these technologies is very relevant. Thus, the objective of this paper is the additive manufacturing of walls with Al-Mg alloy using CMT, CMT-Pulse, PMC, PMC-Mix, and MIG-Pulse, and the evaluation of the hardness, mechanical strength, and porosity of the manufactured parts aiming future industrial applications. The results showed good mechanical properties, small pore fraction, and geometric uniformity of parts produced with PMC and PMC-Mix. MIG-Pulse and PMC parts presented the smaller pore fraction among the GMAW variants, although no difference was noticed in the mechanical properties of the parts.

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