Doctoral Dissertations

Abstract

“An investigation of structure insensitive properties (lattice parameters, thermal expansion coefficients, densities, and imperfections) of silver and the α-phase of the silver-indium system was suggested by the desirable uses for silver and its indium alloys.

Both silver and indium used were 99.999 per cent pure. The silver-indium alloys were prepared by melting both metals inside evacuated and sealed fused quartz tubes. The solidified alloys were annealed and then examined by X-ray diffraction for homogeneity.

This experimental work is divided into three main parts:-

I. X-ray diffraction investigation to determine the solid solubility limit of the Ag-In α-phase at 25° C, the linear thermal expansion coefficients (between 10°- 65° C) and the precise lattice parameters at 25.0° C of silver and of some Ag-In alloys, and to study the effect of impurities on the rate of recovery at room temperature of silver.

II. Precise density measurement of silver and of some Ag-In alloys, and the calculation of the actual number of atoms per unit cell (n') for these samples.

III. X-ray investigation at high temperatures (40°- 900°C) to determine the lattice parameter - temperature relations in vacuum, for 99.999 per cent pure silver and some Ag-In alloys, and to study the effects of different gases (air, N2, O2, and H2) on the thermal expansivity of pure silver.

Each part is discussed separately and at length since the technique used in each one of them is quite different from the two others.

Indium was found to expand the lattice of silver up to 20.3 per cent by weight of indium, which marked the solid solubility limit of the α-phase of the Ag-In system. The linear thermal expansion coefficients of the different Ag-In alloys (between 10°- 65°C) could be represented by the equation: α = [18.73 + 0.02042 (In%) + 0.003576 (In%)2] x 10-6 °C.-1 where (In%) is the weight per cent of indium.

Impurities in silver, present even in small amounts were found to delay its rate of recovery at room temperature.

Vacancies were always present in the α-phase of the Ag-In system, and their amount increased with the increase in the indium content. It was not possible however, to give definitely the reasons of formation or the origin of these vacancies.

The thermal expansion of the lattice of each sample was not linear in nature over a wide range of temperature. Both increasing temperature and increasing indium content were found to increase the linear thermal expansion coefficients (in vacuum) of the Ag-In alloys.

The thermal expansivity of 99.999 per cent pure silver was increased at high temperatures by the presence of nitrogen, oxygen, or both, and nitrogen was more effective than oxygen in this respect. Hydrogen seemed to have no effect in changing the thermal expansivity of 99.999 per cent pure silver as compared with the thermal expansivity in vacuum”--Abstract, pages ii-iv.

Advisor(s)

Straumanis, Martin E., 1898-1973

Committee Member(s)

Frad, William A., 1909-1974

Department(s)

Materials Science and Engineering

Degree Name

Ph. D. in Metallurgical Engineering

Publisher

University of Missouri at Rolla

Publication Date

1964

Pagination

iv, 158 pages

Note about bibliography

Includes bibliographical references (pages 127-131).

Rights

© 1964 Samir Moustafa Riad, All rights reserved.

Document Type

Dissertation - Open Access

File Type

text

Language

English

Thesis Number

T 1571

Print OCLC #

9526491

Download

Included in

Metallurgy Commons

Share

 
COinS