Analysis of dislocation pipe diffusion in deformed alpha-phase PdHX using a synthesized QENS approach

Serio, Joseph Anthony

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https://hdl.handle.net/2142/99282 Copy

Description

Title

Analysis of dislocation pipe diffusion in deformed alpha-phase PdHX using a synthesized QENS approach

Author(s)

Serio, Joseph Anthony

Issue Date

2017-09-05

Director of Research (if dissertation) or Advisor (if thesis)

Heuser, Brent

Committee Member(s)

Zhang, Yang

Department of Study

Nuclear, Plasma, & Rad Engr

Discipline

Nuclear, Plasma, Radiolgc Engr

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

M.S.

Degree Level

Thesis

Keyword(s)

• Dislocation pipe diffusion
• Hydrogen
• Palladium
• QENS
• neutron scattering

Abstract

Using quasielastic neutron scattering results from multiple spectrometers, material considerations are made for annealed and deformed PdH_x with sufficiently low [H] as to encourage the process of dislocation pipe diffusion (DPD) below a critical temperature. The results of this analysis indicate that the simultaneous comparison of QENS results from instrument with different instrumental resolution and energy transfer window can provide a more comprehensive picture of the diffusive modes seen within a system than using the instruments independently. A method is developed for accurately comparing the dynamic structure factor S_inc(Q,E) data of multiple instruments, using an inverse Fourier transform in order to obtain the intermediate scattering function F_inc(Q,t) for each instrument and simultaneously analyzing the output from three QENS spectrometers. An array of models are approached to describe the combined F_inc(Q,t), with the best description of F_inc(Q,t) for the deformed PdH_x found to be a summed KWW/single exponential fit. The results show that the DPD contribution to the F_inc(Q,t) can be well described using a stretched exponential (KWW) mode, which is qualitatively correlated to the heterogeneity of the diffusive modes expected for the near-core and inner core region of heavily deformed Pd.

Graduation Semester

2017-12

Type of Resource

text

Permalink

http://hdl.handle.net/2142/99282

Copyright and License Information

2017 by Joseph Anthony Serio. All rights reserved.

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