Characterization of Ageing Products in AA6111 Using Dynamic Dislocation-Defect Analysis

2006 ◽  
pp. 777-782
Author(s):  
S. Saimoto ◽  
S. Subbaiyan ◽  
C. Gabryel
Keyword(s):  
Defect Analysis ◽  
Dislocation Defect ◽  
Dynamic Dislocation

Characterization of Ageing Products in AA6111 Using Dynamic Dislocation-Defect Analysis

2006 ◽  
Vol 519-521 ◽  
pp. 777-782
Author(s):  
Shigeo Saimoto ◽  
S. Subbaiyan ◽  
C. Gabryel
Keyword(s):  
Volume Fraction ◽  
Deformation Mode ◽  
Artificial Ageing ◽  
Defect Analysis ◽  
Dislocation Defect ◽  
The Mean ◽  
Sufficient Strength ◽  
Dynamic Dislocation ◽  
Strength And Ductility

In dynamic dislocation-defect analysis, the thermodynamic deformation-mode signatures are examined as the ageing proceeds. In this method, the activation volume (ν) and the mean slip distance (λ) is simultaneously determined with the flow stress (τ) such that the inverse workhardening slope (1/θ) can be plotted versus b2λ/ν where b is the Burgers vector. The slope of this almost linear locus is directly proportional to the activation distance (d). Calibration with a model alumina-dispersed high conductivity copper reveals that punched-out loops are produced up to failure and is represented by a linear locus from 0.1 to 11 % strain. Artificial ageing of AA6111 at 180°C follows this pattern but the naturally-aged specimen manifest a distinctly different signature which shows a transition as the GP zone-type precipitates are sheared. Furthermore by selecting a suitable tensile-test temperature below 250K, the particle size and volume fraction can be determined if particle shearing does not take place. The optimum size and volume fraction necessary for sufficient strength and ductility can be assessed using this method.

Dynamic Dislocation-Defect Analysis and SAXS Study of Nanovoid Formation in Aluminum Alloys

2008 ◽  
Vol 130 (2) ◽  
Author(s):  
L. Westfall ◽  
B. J. Diak ◽  
M. A. Singh ◽  
S. Saimoto
Keyword(s):  
Volume Fraction ◽  
Thermomechanical Processing ◽  
Pure Aluminum ◽  
Void Formation ◽  
Defect Analysis ◽  
Stress Concentrations ◽  
X Ray Scattering ◽  
Cu Alloys ◽  
Dislocation Defect ◽  
Dynamic Dislocation

Crystalline defects other than the essential dislocations are produced by dislocation intersections resulting in debris, which can transform into loops, point defects, and∕or nanovoids. The stress concentrations ahead of slip clusters promote void formation leading to incipient cracks. To evaluate the progression of these processes during deformation, dynamic dislocation-defect analysis was applied to nominally pure aluminum, Al–Mg, and Al–Cu alloys. In the case of nanovoid formation, small angle X-ray scattering (SAXS) was used to quantitatively assess if the void size and its volume fraction can be determined to directly correlate with the measured thermodynamic response values. The SAXS signal from the nanovoids in nominally pure aluminum is distinctly measurable. On the other hand, thermomechanical processing of even nominally pure aluminum results in the formation of nanoprecipitates, which requires future calibration.

Dynamic Evaluation of Strength-Structure Properties by the Determination of Activation Volume and Mean Slip Distance

2007 ◽  
Vol 539-543 ◽  
pp. 2192-2197 ◽  
Author(s):  
Shigeo Saimoto
Keyword(s):  
Activation Volume ◽  
Rate Sensitivity ◽  
Defect Analysis ◽  
Fine Grained ◽  
Dislocation Defect ◽  
Defect Mobility ◽  
Dynamic Dislocation ◽  
Slip Distance ◽  
Structure Properties

Measurements of the activation volume and mean slip distance were used in the dynamic dislocation-defect analysis to reveal the dislocation-obstacle evolution with strain. Due to the large effect of point defect mobility above 250 K on the strain rate sensitivity, fine-grained Al specimens with the grain-boundaries sealed and unsealed as vacancy sinks were tested at 300 K as the reference behaviour. The activation distance diagrams revealed that the artificially aged products in AA6111 and naturally aged extruded AA6063 can be used to examine the effect of chopping-up of particles on the ductility of the samples. Thus a means to examine strength-structure-ductility of specific products have been devised.

scholarly journals Entropy Generation Methodology for Defect Analysis of Electronic and Mechanical Components—A Review

Entropy ◽  
2020 ◽  
Vol 22 (2) ◽  
pp. 254
Author(s):  
Miao Cai ◽  
Peng Cui ◽  
Yikang Qin ◽  
Daoshuang Geng ◽  
Qiqin Wei ◽  
...  
Keyword(s):  
Entropy Generation ◽  
Electronic Devices ◽  
Second Law Of Thermodynamics ◽  
Damage Analysis ◽  
Defect Analysis ◽  
Unique Role ◽  
Mechanical Components ◽  
Assessment Problems ◽  
The Relationship

Understanding the defect characterization of electronic and mechanical components is a crucial step in diagnosing component lifetime. Technologies for determining reliability, such as thermal modeling, cohesion modeling, statistical distribution, and entropy generation analysis, have been developed widely. Defect analysis based on the irreversibility entropy generation methodology is favorable for electronic and mechanical components because the second law of thermodynamics plays a unique role in the analysis of various damage assessment problems encountered in the engineering field. In recent years, numerical and theoretical studies involving entropy generation methodologies have been carried out to predict and diagnose the lifetime of electronic and mechanical components. This work aimed to review previous defect analysis studies that used entropy generation methodologies for electronic and mechanical components. The methodologies are classified into two categories, namely, damage analysis for electronic devices and defect diagnosis for mechanical components. Entropy generation formulations are also divided into two detailed derivations and are summarized and discussed by combining their applications. This work is expected to clarify the relationship among entropy generation methodologies, and benefit the research and development of reliable engineering components.

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