Dissolution and Growth of Precipitates Under Electron Irradiation in an Al-11.8 at % Zn Alloy by Small Angle Neutron Scattering.

1994 ◽  
Vol 376 ◽  
Author(s):  
M.R. Baig
Keyword(s):  
Neutron Scattering ◽  
Electron Irradiation ◽  
Small Angle ◽  
Small Angle Neutron Scattering ◽  
Diffusion Mechanism ◽  
Precipitate Size ◽  
Low Doses ◽  
Radiation Enhanced Diffusion ◽  
The Matrix ◽  
Zn Alloy

ABSTRACTDissolution and growth of precipitates in a room temperature aged Al-11.8 at % Zn alloy have been studied under electron irradiation using small angle neutron scattering (SANS). A series of electron irradiations were performed on each sample and SANS measurements were made on each irradiation. In general for low doses the results show an initial decrease in the magnitude of the scattering, but associated with an increase in the precipitate size. This is followed on prolonged irradiation by an increase in the magnitude of the scattering with a continued increase in precipitate size. It is believed, that at low doses some precipitate grow in size but others may dissolve in the matrix, which then becomes supersaturated. With the enhanced rate of diffusion as a result of the irradiation, the remaining precipitates grow rapidly. As the supersaturation reduces, a coarsening mechanism takes over, via a radiation enhanced diffusion mechanism.

Evaluation of Nanosize NbC Precipitates in HSLA Steel through Microstructural Analysis and Small Angle Neutron Scattering

2018 ◽  
Vol 941 ◽  
pp. 141-146
Author(s):  
Haruo Nakamichi ◽  
Katsumi Yamada ◽  
Kaneharu Okuda ◽  
Toshinori Ishida ◽  
Masato Ohnuma
Keyword(s):  
Neutron Scattering ◽  
Small Angle ◽  
Small Angle Neutron Scattering ◽  
Hsla Steel ◽  
Microstructural Analysis ◽  
Magnetic Scattering ◽  
Precipitate Size ◽  
Steel Matrix ◽  
Orientation Relationships ◽  
Hardening Mechanism

Nano size precipitate morphologies are very important for considering the precipitate hardening mechanism of HSLA steels. Systematic analysis of precipitates from nano scale to bulk scale were carried out using Nb bearing hot rolled steels through transmission electron microscopy (TEM) observations and chemical analysis of precipitates by solvent extraction. A small angle neutron scattering (SANS) experiment was also performed using a Hokkaido Univ. compact neutron source to understand average precipitate size. Results show that both changes in hardness and the amount of precipitates (under 20nm in size) have the same tendency. Precipitate is recognized as NbC plates, which have coherency with the steel matrix by Baker-Nutting orientation relationships. A row of precipitates, formed on the interface between austenite and ferrite during transformation, is also apparent. The SANS profile shows that small size precipitate formation is detected even though the amount of precipitation is small. In addition, the magnetic scattering component of the SANS profile has high sensitivity to NbC precipitates compared with that of the nucleus scattering component. By comparing precipitate data from comprehensive experiments, we consider the relationship between precipitate behavior and the hardening mechanism.

scholarly journals Positron Annihilation Spectroscopy and Small Angle Neutron Scattering Characterization of Nanostructural Features in Irradiated Fe-Cu-Mn Alloys

2000 ◽  
Vol 650 ◽  
Author(s):  
B. D. Wirth ◽  
P. Asoka-Kumar ◽  
R. H. Howell ◽  
G. R. Odette ◽  
P. A. Sterne
Keyword(s):  
Neutron Scattering ◽  
Positron Annihilation ◽  
Small Angle ◽  
Small Angle Neutron Scattering ◽  
Nuclear Reactor ◽  
Positron Annihilation Spectroscopy ◽  
Peak Hardness ◽  
The Matrix ◽  
Complementary Techniques

ABSTRACTRadiation embrittlement of nuclear reactor pressure vessel steels results from a high number density of nanometer sized Cu-Mn-Ni rich precipitates (CRPs) and sub-nanometer matrix features, thought to be vacancy-solute cluster complexes (VSC). However, questions exist regarding both the composition of the precipitates and the defect character and composition of the matrix features. We present results of positron annihilation spectroscopy (PAS) and small angle neutron scattering (SANS) characterization of irradiated and thermally aged Fe-Cu and Fe-Cu-Mn alloys. These complementary techniques provide insight into the composition and character of both types of nanoscale features. The SANS measurements indicate populations of CRPs and VSCs in both alloys. The CRPs are coarser in the Fe-Cu alloy and the number densities of CRP and VSC increase with the addition of Mn. The PAS involved measuring both the positron lifetimes and the Doppler broadened annihilation spectra in the high momentum region to provide elemental sensitivity at the annihilation site. The spectra in Fe-Cu-Mn specimens thermally aged to peak hardness at 450°C and irradiated at 288°C are nearly identical to elemental Cu. Positron lifetime and spectrum measurements in Fe-Cu specimens irradiated at 288°C clearly show the existence of long lifetime (∼500 ps) open volume defects, which also contain Cu. Thus the SANS and PAS provide a self-consistent picture of nanostructures composed of CRPs and VSCs and tend to discount high Fe concentrations in the CRPs.

Nano Precipitate Analysis of X80 Pipeline Steel Using Small Angle Neutron Scattering

2006 ◽  
Author(s):  
J. B. Wiskel ◽  
D. G. Ivey ◽  
H. Henein
Keyword(s):  
Neutron Scattering ◽  
Size Distribution ◽  
Small Angle ◽  
Small Angle Neutron Scattering ◽  
Pipeline Steel ◽  
Precipitate Size ◽  
Processing Conditions ◽  
Coiling Temperature ◽  
X80 Pipeline Steel ◽  
Finish Rolling

An understanding of precipitate size distribution and its evolution with processing conditions is important with regards to the final mechanical properties of microalloyed pipeline steel. A study was undertaken using small angle neutron scattering (SANS) to quantify the size distribution of nano-sized precipitates in X80 pipeline steel. The distributions obtained for different X80 samples were correlated with the finish rolling temperature and final coiling temperature as a means of identifying processing conditions that may enhance fine precipitate evolution. The precipitate distribution predicted for Grade 100 steel using SANS data is compared to data obtained from a TEM particle counting analysis.

Sign in / Sign up

Export Citation Format

Share Document