Masters Theses

Abstract

"In several metals the process of recrystallization is accompanied by a change in the orientation of the recrystallized material with respect to the cold rolled material. If the change is sufficiently large, the changing position of the crystals can be determined by measuring the change in the intensity of the characteristic Bragg-reflection with a Geiger counter x-ray spectrometer. Recent determinations of the activation energies of copper and a 50/50 iron-nickel alloy have been made by using this x-ray technique. Both of these metals show a decided shift in the orientation as the material is recrystallized.

Silver was examined to find out the possibilities of application of this x-ray technique to metals with a more complex textural change. It is known that the crystalline texture in severely cold rolled silver can be described by saying that the [112] direction of the face centered cubic crystal is aligned approximately in the rolling direction and that faces of the form (110) lie approximately in the rolling plane. On complete recrystallization the [112] direction aligns itself approximately in the cross rolling direction and faces of the form (113) lie approximately in the rolling plane. This shift in the orientation from the cold rolled to the recrystallized state is a fair indication that the above mentioned x-ray technique could be applied to silver for the determination of its activation energy of recrystallization.

Since recrystallization is not an instantaneous process, it may be stopped at various stages of its progress and the change in orientation determined by accurately measuring the change in the intensity of the x-ray lines. A plot of time versus percent recrystallization can thus be made. By determining these recrystallization rate curves at several temperatures, the activation energy of the process can be calculated.

In this examination five different temperatures of recrystallization were employed and sufficient number of samples were prepared to follow the course of recrystallization completely by measuring the changes of x-ray line intensities at various stages. Although (220) and (113) line intensities were measured, the calculations were based on (113) line measurements, while (220) line measurements were used as a check for the (113) line values.

Silver of 99.97% purity was used in this investigation. Since the recrystallization process is considerably affected by impurity content, the results of this investigation apply only to silver of a similar composition. This metal after 96.55% cold rolling was found to yield a value of 24.1 ± 1.5 Kcal/gm mole as its activation energy"--Introduction, pages 1-2.

Advisor(s)

Eppelsheimer, Daniel S., 1909-1988

Department(s)

Materials Science and Engineering

Degree Name

M.S. in Metallurgical Engineering

Publisher

Missouri School of Mines and Metallurgy

Publication Date

1952

Pagination

v, 49 pages

Note about bibliography

Includes bibliographical references (pages 46-48).

Rights

© 1952 Krishan K. Tangri, All rights reserved.

Document Type

Thesis - Open Access

File Type

text

Language

English

Subject Headings

Recrystallization (Metallurgy)SilverRolling (Metal-work)

Thesis Number

T 1031

Print OCLC #

5916039

Electronic OCLC #

933763458

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