A study on Al 2219 alloy precipitate growth rates by non-linear ultrasonic technique

2020 ◽  
Vol 62 (11) ◽  
pp. 656-661
Author(s):  
Jun You ◽  
Yunxin Wu ◽  
Hai Gong
Keyword(s):  
Interaction Model ◽  
Model Alloy ◽  
Linear Coefficient ◽  
Precipitated Phase ◽  
Coherent Precipitate ◽  
Precipitate Growth ◽  
Non Linear ◽  
Generation Of Harmonics ◽  
Precipitation Phase ◽  
Ultrasonic Parameter

A non-linear ultrasonic study has been carried out to characterise the variation in precipitation phase. An age-hardenable aluminium alloy (2219) has been taken as a model alloy for the present investigation. It is shown that there is a strong correlation between the change in the non-linear coefficient and the change in the precipitated phase. The observed variations in the non-linear ultrasonic parameter have been explained by modifying an existing dislocation-coherent precipitate interaction model for the generation of harmonics in order to account for a weaker dislocation-semicoherent precipitate interaction. In general, the model proposed can be applicable to all precipitation-hardenable alloy systems undergoing coherent to incoherent precipitate phase transition.

The Effect of the SiC Content on Electrical Properties of SiC Anti-Corona Coating for Generator

2016 ◽  
Vol 868 ◽  
pp. 23-27
Author(s):  
Liang Liang Nie ◽  
Hang Zhou ◽  
Shi Di Tao ◽  
Yu Feng Li ◽  
Peng Zhang ◽  
...  
Keyword(s):  
Electrical Properties ◽  
Surface Resistivity ◽  
Initial Surface ◽  
Mass Ratio ◽  
Linear Coefficient ◽  
Non Linear ◽  
Suitable Amount ◽  
Corona Structure

In this research, the anti-corona lacquer with different SiC content was fabricated. The surface resistivity of the lacquer at different voltage levels was measured, and the effect of the SiC content on electrical properties of SiC anti-corona coating was investigated. The results showed that the initial surface resistivity ρs decreased with increasing mass ratio of SiC to resin, while the non-linear coefficient β varied the opposite way. The surface resistivity was improved by adding suitable amount of graphite, which suited the requirements of multiple sections anti-corona structure.

Numerical analysis of the dynamic interaction between a non-pneumatic mechanical elastic wheel and soil containing an obstacle

2016 ◽  
Vol 231 (6) ◽  
pp. 731-742 ◽  
Author(s):  
Xianbin Du ◽  
Youqun Zhao ◽  
Qiang Wang ◽  
Hongxun Fu
Keyword(s):  
Finite Element ◽  
Three Dimensional ◽  
Interaction Model ◽  
Dynamic Interaction ◽  
Constitutive Law ◽  
Elastic Wheel ◽  
Non Linear ◽  
Dimensional Finite Element ◽  
Mechanical Elastic Wheel ◽  
Three Dimensional Finite Element

An innovative non-pneumatic tyre called the mechanical elastic wheel is introduced; significant challenges exist in the prediction of the dynamic interaction between this mechanical elastic wheel and soil containing an obstacle owing to its highly non-linear properties. To explore the mechanical properties of the mechanical elastic wheel and the soil, the finite element method is used, and a non-linear three-dimensional finite element wheel–soil interaction model is also established. Hyperelastic incompressible rubber, which is one of the main materials of the mechanical elastic wheel, is analysed using the Mooney–Rivlin model. The modified Drucker–Prager cap plasticity constitutive law is utilized to describe the behaviour of the soil, and the obstacle is represented as an elastic body. Simulations with different rotational speeds of the mechanical elastic wheel were conducted. The stress distribution and the displacement of the mechanical elastic wheel and the soil were obtained, and the effects of different rotational speeds on the displacement, the velocity and the acceleration of the hub centre are presented and discussed in detail. These results can provide useful information for optimization of the mechanical elastic wheel.

Soil-Structure Interaction of Heated Pipeline Buried in Soft Clay

2002 ◽  
Author(s):  
Alvaro Maia da Costa ◽  
Carlos de Oliveira Cardoso ◽  
Claudio dos Santos Amaral ◽  
Alejandro Andueza
Keyword(s):  
Challenging Behavior ◽  
Soft Clay ◽  
Back Analysis ◽  
Interaction Model ◽  
Material Behavior ◽  
Soil Reaction ◽  
Inelastic Behavior ◽  
Guanabara Bay ◽  
Structure Interaction ◽  
Non Linear

Heated pipelines buried in soft clay can develop a very challenging behavior. The thermal expansion of the pipelines normally induces buckles, which will be supported by the passive soil reaction. The buckles of the pipelines in soft clay can generate a non-linear inelastic behavior that is an unstable situation named “snap through”. In such situation the pipeline can jump from a configuration of a few centimeters displacement to another of meters displacement. Once the snap through situation has developed, there is the possibility of a local pipeline buckling, causing the pipeline rupture and as a consequence an oil spill. This paper presents the results obtained during the analysis of the rupture of a buried heated pipeline in the Guanabara Bay of Rio de Janeiro, Brazil. A very sophisticated procedure including a simulation of the thermal mechanical interactions between the soil and the pipeline structure was developed for back analysis of the thermal inelastic pipeline buckling. Computer modeling was carried out using the finite element method considering of the non-linear material behavior of the soil and pipeline, and nonlinear geometrical behavior of the pipeline. A cyclic thermal-mechanical soil-pipeline structure interaction model was the challenging aspect of the simulation, that explains the trigger mechanism of the snap through behavior of heated pipelines, which was responsible for the rupture of the pipeline in Guanabara Bay.

Nano-Precipitated Phase and Evolution of Al-Cu-Mg Alloy Subjected to Rapid Cold Stamping

2019 ◽  
Vol 11 (9) ◽  
pp. 1318-1326
Author(s):  
Caihe Fan ◽  
Ling Ou ◽  
Jianjun Yang ◽  
Xihong Chen
Keyword(s):  
Boundary Diffusion ◽  
Hardness Test ◽  
S Phase ◽  
Mg Alloy ◽  
Fine Grained ◽  
Precipitated Phase ◽  
Transmission Electron ◽  
Three Stages ◽  
Cold Stamping ◽  
Precipitation Phase

High-resolution transmission electron microscopy, energy dispersive spectroscopy, and hardness test were used to study the nano-precipitates and evolution of nano-precipitation of the sprayformed fine-grained Al-Cu-Mg alloy during rapid cold stamping deformation. Results show that the elongated S-phase and the acicular ' phase of the Al-Cu-Mg alloy after three passes of cold stamping of rapid cold-shock deformation undergoes re-dissolution, and a large number of the fine granular balance  phases are precipitated after four passes of rapid cold-stamping deformation. The main mechanism of low-temperature re-dissolution of S' phase and ' phase in Al-Cu-Mg alloy induced by rapid cold stamping deformation is the precipitation phase fracture, grain boundary diffusion, and vacancy diffusion. The change in the hardness of the alloy during rapid cold stamping deformation is affected by the combination of phase-resolving softening, work hardening, and reprecipitation strengthening and increases at three stages. The hardness increases from 55 HB to 125 HB, which is increased by 127%.

Early Stages of Precipitation in γ' Phase of a Ni–Al–Ti Model Alloy: Phase-Field and First-Principles Study

2020 ◽  
Vol 12 (5) ◽  
pp. 746-754
Author(s):  
Yuanyang Sun ◽  
Yuhong Zhao ◽  
Huijun Guo ◽  
Xiaolin Tian ◽  
Hua Hou
Keyword(s):  
Phase Field ◽  
First Principles ◽  
Ostwald Ripening ◽  
Metastable Phase ◽  
Model Alloy ◽  
Precipitation Process ◽  
Site Preference ◽  
Precipitation Mechanism ◽  
Early Stages ◽  
Precipitated Phase

The early stages of precipitation process of the γ' phase of a Ni–Al–Ti alloy are investigated by microscopic phase-field and first-principles calculations. The simulated results indicate that a pre-precipitate with L10 structure appears before the L12 ordered phase, and then this metastable phase gradually transforms to L12 ordered phase; finally, the precipitated phase is composed of γ' ordered phase and γ matrix phase. The occupation probabilities of Al, Ni, and Ti atoms also illustrate the formation of the L10 phase and its situ conversion to L12 ordered phase constituted by a complicated compound Ni3(AlTi). Through the analyses of order parameter and occupation probability, the precipitation mechanism of γ' phase is drawn as a combination of congruent ordering and destabilization decomposition. Meanwhile, we also find that the growth and coarsening of the γ' phase occur via mixed mechanisms of Ostwald ripening and coalescence coarsening of neighboring precipitates. Moreover, the first-principles method is applied to calculate the thermodynamic parameters and validate further the appearance of the metastable phase and the site preference of Ti atom, which offers an explanation for atomic occupancy characteristics in the precipitate.

Wavelength dependence of the third order non-linear coefficient in hydrothermally grown ZnO crystals

2004 ◽  
Vol 1 (4) ◽  
pp. 997-1000 ◽  
Author(s):  
A. Zappettini ◽  
F. D'Amore ◽  
S. M. Pietralunga ◽  
A. Terio ◽  
M. Martinelli ◽  
...  
Keyword(s):  
Wavelength Dependence ◽  
Third Order ◽  
Linear Coefficient ◽  
The Third ◽  
Non Linear

Precipitation Phase and Impurities Distribution of Metallurgical Grade Silicon by Vacuum Refining Followed Slag Treatment

2013 ◽  
Vol 813 ◽  
pp. 492-496
Author(s):  
Hui Xian Lai ◽  
Liu Qing Huang ◽  
Ming Fang ◽  
Cheng Hao Lu ◽  
Juan Chen ◽  
...  
Keyword(s):  
Saturated Vapor Pressure ◽  
Saturated Vapor ◽  
Impurity Phase ◽  
Metallurgical Grade Silicon ◽  
Vacuum Refining ◽  
Precipitated Phase ◽  
Slag Treatment ◽  
Precipitated Phases ◽  
Precipitation Phase ◽  
Main Impurity

Precipitation phase and impurities distribution of MG-silicon were investigated by vacuum refining followed by slag treatment, and the CaO-SiO2-CaF2 system was adopted for slag treatment. Contrasting the microstructure of precipitated phase in slag treatment with and without vacuum refining pretreated, it could be concluded that the composition of precipitated phases, obtained in MG-Si after vacuum refining followed slag treatment, only consisted of Ca-rich intermetallic silicide phases such as Si-Ca-Ni, Si-Ca-Fe and main impurity phase Si-Ca. And the vacuum refining could make an increase in concentration of the impurity Ti due to its low saturated vapor pressure and silicon loss, which was in favor of the interaction with the impurity B, resulting in the formation of TiB2 that could stay at the slag. Consequently, the vacuum refining could be regarded as an effective method for facilitating the removal of B from MG-Si with slag treatment.

Sign in / Sign up

Export Citation Format

Share Document