Masters Theses

Abstract

"Melting of micron-sized (0.2 to 3 µm diameter) indium particles embedded in an aluminum matrix was discovered to produce acoustic emission. Melting of embedded immiscible particles produces a pure dilation during the phase transformation and has no long-range diffusion field to control the speed of transformation. It was found that acoustic emission can no longer be considered as a criterion of displacive transformations and that melting of micron-sized embedded particles is strain energy controlled. Acoustic emission was confirmed to result from the rapid relaxation of aluminum around indium particles embedded on grain boundaries. Prismatic punching of dislocation loops is proposed as the mechanism for volume accommodation during melting of the embedded indium particles. The resulting dislocation density was calculated to range between 3.5 x 10⁸ and 4.1 x 10⁹ cm⁻². Prior thermal history was found to affect the acoustic emission during melting of the embedded particles, and all effects could be explained in terms of a dislocation model. Analysis following the Eshelby inclusion model shows that acoustic emission and strain-controlled transformations are expected for particles 0.1 to 18 µm in diameter. It is suggested that any phase transformation associated with a volume change and matrix relaxation may generate acoustic emission when the transformation occurs rapidly enough. It is also suggested that liquid inclusions act as a free surface within higher-melting point matrices and facilitates dislocation nucleation"--Abstract, page iv.

Advisor(s)

Van Aken, David C.

Committee Member(s)

Huebner, Wayne
OKeefe, Matt

Department(s)

Materials Science and Engineering

Degree Name

M.S. in Metallurgical Engineering

Sponsor(s)

American Iron and Steel Institute
National Science Foundation (U.S.)

Publisher

Missouri University of Science and Technology

Publication Date

Summer 2012

Journal article titles appearing in thesis/dissertation

  • Analysis of acoustic emission during the melting of embedded indium and aluminum: a study of plastic strain accommodation during phase transformation

Pagination

x, 72 pages

Rights

© 2012 Michael Masao Kuba, All rights reserved.

Document Type

Thesis - Open Access

File Type

text

Language

English

Subject Headings

Acoustic emissionDislocations in metalsMetal-insulator transitionsStrains and stresses

Thesis Number

T 10054

Print OCLC #

828929218

Electronic OCLC #

795715405

Download

Included in

Metallurgy Commons

Share

 
COinS