Material Type  

 학위논문

 

0016935202

Date and Time of Latest Transaction  

20240214101905

ISBN  

9798380713023

DDC  

741

Author  

Abouelella, Hamdy Salah.

Title/Author  

High-Temperature Mechanical Properties of Accident-Tolerant Fuel Cladding Materials - [electronic resource]

Publish Info  

[S.l.] : North Carolina State University., 2023

Publish Info  

Ann Arbor : ProQuest Dissertations & Theses, 2023

Material Info  

1 online resource(146 p.)

General Note  

Source: Dissertations Abstracts International, Volume: 85-05, Section: B.

General Note  

Advisor: He, Lingfeng;Beeler, Benjamin;Murty, Korukonda.

학위논문주기  

Thesis (Ph.D.)--North Carolina State University, 2023.

Restrictions on Access Note  

This item must not be sold to any third party vendors.

Abstracts/Etc  

요약This thesis is on the creep behavior of high Cr-containing FeCrAl Advanced Powder Metallurgy Tubing (APMT) and 14YWT-NFA1 alloys. The observed APMT creep behavior revealed a transition between three regions. The first region at low stresses was characterized by dislocation viscous glide with a stress-exponent (nI) of 2.8 and activation energy (QI) of 252.7 kJ/mol. The second region at intermediate stresses has a stress exponent (nII) equal to ~ 7.45 and a high activation energy (QII) of 576 kJ/mol. The high stress third region is characterized by a high stress exponent (nIII) of 14.4 and high activation energy (QIII) of 737.97±18.7 kJ/mol.The threshold stress approach was employed to determine the dominant creep mechanism at the upper range of the examined stresses. Based on this analysis, dislocation-climb over precipitates facilitated by the increase in dislocation line length was found to be the creep ratecontrolling mechanism at higher stresses, with a creep stress exponent of 6 and an activation energy of 252.8 ± 20.0 kJ/mol.The modified Bird-Mukherjee-Dorn (BMD) equation was also utilized to find the stress exponent that best fit the data. The rate-controlling mechanism based on modified BMD equation was determined to be the dislocation-climb with a stress exponent equal to 6 in agreement with the results from the threshold stress approach.The microstructural characterization of the APMT alloy provided preliminary evidence of the formation of (Cr, Mo)-rich carbides at the grain boundaries. The segregation observed might assist in locking the grain boundaries from sliding, thereby augmenting the overall strength of the material.The 14YWT-NFA1 creep study revealed unique characteristics, featuring a transition between two distinct regions. The stress exponent n, is approximately one in the low stress region, coupled with the activation energy Q = 244.58 kJ/mol, suggesting the dominance of NabarroHerring lattice diffusion-controlled creep mechanism at lower stresses. In the high stress region, however, a stress exponent of around 15 and an activation energy Qof 388.56 kJ/mol highlight the role of precipitates as dislocation barriers.BF-TEM images revealed that the grain structure remained stable due potentially to the presence of precipitates along the grain boundaries. Another observation was the existence of two distinct types of precipitates, W-rich and Y-Ti-O rich, which never co-occurred on the same grain boundary in the characterized area. The TEM-EDS mapping for W after creep tests demonstrated concentrated localizations at the grain boundaries with no signs of W inside the grains. In addition to that, the 14YWT-NFA1 alloy exhibits inherent microstructural deficiencies such as voids and micro-cracks in the as-received condition.Molecular dynamics investigations analyzed the effect of Cr and Al on the ductility of FeCrAl system. The process started by verifying the reliability and accuracy of the interatomic potential used for the simulations accomplished through a series of tests, including lattice parameter calculations, and melting temperature using both single and two-phase melting methods. The impact of changing the Cr and Al content on the ductility of the FeCrAl supercell was studied and a local compositional space with Cr content of 18 at.

Subject Added Entry-Topical Term  

Nuclear energy.

Subject Added Entry-Topical Term  

Design.

Subject Added Entry-Topical Term  

Nuclear reactors.

Subject Added Entry-Topical Term  

Deformation.

Subject Added Entry-Topical Term  

Energy.

Subject Added Entry-Topical Term  

Nuclear engineering.

Subject Added Entry-Topical Term  

Nuclear physics.

Subject Added Entry-Topical Term  

Physics.

Added Entry-Corporate Name  

North Carolina State University.

Host Item Entry  

Dissertations Abstracts International. 85-05B.

Host Item Entry  

Dissertation Abstract International

Electronic Location and Access  

로그인을 한후 보실 수 있는 자료입니다.

소장사항  

202402 2024

Control Number  

joongbu:643891