Characterization of Alurninum Alloy 2618 and Its Composites Containing Numina Particles

200 Pages·1999·8.28 MB·English

Characterization of Alurninum Alloy 2618 and Its Composites
Containing Numina Particles
A Thesis Submitted to the ColIege of Graduate Studies and Research
in Partial Fulfillment of the Requirements
for the Degree of Doctor of Philosophy
in the Department of Mechanical Engineering
University of Saskatchewan
Saskatoon
BY
Ikechukwuka N. A. Oguocha
Spring 1999
O Copyright Ikechukwuka N. A. Oguocha, 1998. Ail rights reserved.
I*I National Librâry Bibliothèque nationale
of Canada du Canada
Acquisitions and Acquisitions et
Bibliogaphic Services services bibliographiques
395 Wellington Street 395, rue Wellington
Ottawa ON KI A ON4 Ottawa ON K1A ON4
canada Canada
Yom lüe Votre drence
Our W Nom reference
The author has granted a non- L'auteur a accordé une licence non
exclusive licence allowing the exclusive permettant à la
National Library of Canada to Eibliothèque nationale du Canada de
reproduce, loan, distribute or sell reproduire, prêter, distribuer ou
copies of this thesis in microfonn, vendre des copies de cette thèse sous
paper or electronic formats. la fome de microfiche/nlm, de
reproduction sur papier ou sur format
électronique.
The author retains ownership of the L'auteur conserve la propriété du
copyright in this thesis. Neither the droit d'auteur qui protège cette thèse.
thesis nor substantial extracts from it Ni la thèse ni des extraits substantiels
may be printed or otherwise de celle-ci ne doivent être imprimés
reproduced without the author's ou autrement reproduits sans son
permission. autorisation.
UNIVERSITY OF SASKATCHEWAN
Coilege of Graduate Studies and Research
SUMMARY OF DISSERTATION
Submitted in Partial Fulfdlment
Of the Requirements for
DEGREE OF DOCTOR OF PEEOSOPHY
by
Ikechukwuka Oguocha
Department of Mechanical Engineering
University of Saskatchewan
Summer, 1998
Dr. J.A. Gillies Dean's Designate, Chair
College of Graduate Studies and Research
Dr. S. Yannacopoulos Department of Mechanical Engineering
Dr. C. Sargent Department of Mechanical Engineering
Dr. B. Hertz Department of Mechanical Engineering
Dr. T, Rezansoff Department of Civil Engineering
Externai Examiner:
Dr. A. K. Gupta
AIcm International Ltd.
Kingston Research & Development Centre
Kingston, Ontario K7L 5L9
PERMISSION TQ USE
Whereas this thesis is submitted in partial fuifihent of the requirements for the degree
of Doctor of Philosophy fiom the University of Saskatchewan, the author has agreed that
the Libraries of this University may make it fieeiy available for inspection. Further, the
author has agreed that permission for copying of this thesis for scholarly purposes may
be granted by the professor who supervised the thesis work reported herein or, in his
absence, by the Head of the Department or the Dean of the College in which the thesis
work was carried out. It is understood that any copying or publication or use of this
thesis or parts thereof for financial gain shall not be allowed without the author's written
permission. Furthemore, it is understood that due recognition shaU be given to the
author and to the University of Saskatchewan in any scholarly use which may be made
of any materid in this thesis.
Requests for permission to copy or make other use of material in this thesis in whole or
part should be addressed to:
Head of the Department of Mechanical Engineering
57 Campus Drive
University of Saskatchewan
Saskatoon, Canada S7N 5A9
Metal matrix composites (MMCs) combine a stiff but brittle phase, typically a cerarnic,
with a more ductile metal ma&. The correct fractional combination of materials cm
resuit in a material with irnproved stiffness, creep resistonce, yield stress, and Wear
resistance relative to the monolithic matrix. The use of MMCs in recent years has
become more widespread due to a growing understanding of the dependence of
composite properties on a number of factors (e.g., interface properties, metailurgy of the
matrix, and stress partitioning between the constituent phases) and appreciation of the
problems that can occur in their usage. The purpose of this work was to investigate
rnicrostnictural evolution in ingot metallurgy AA2618 due to the addition of 10 and 15
vol. % angular dumina (A1203)p articles.
The primary investigative techniques employed were microhardness measurements,
differential scanning calorimetry (DSC), scanning electron rnicroscopy (SEM), electron
probe microanalysis (EPMA), and transmission electron rnicroscopy (TEM). In addition,
other metallographic and data analysis techniques were used.
The results of this study showed that the addition of N103p articles did not alter the
aging sequence of AA2618, but it altered certain aspects of the precipitation reaction. It
caused the suppression of Guinier-Preston-Bagaryatskii (GPB) zone nucleation,
acceleration of the artificial aging response, lowering of peak hardness value, and non-
unifonn distribution of precipitate and dispersoid phases. However, it did not affect the
growth mechanisms for S' and 9' formation. The gowth parameters obtained for the
unreinforced ailoy and its composites were not significantly different.
Magnesium accumulation around the reinforcing &O3 particles was very prouounced.
Mg-rich intermetdlic particles (suggested to be MgA1204s pinel) were observed existing
in isolation and embedded in Al,O, particles. The presence of these particles was
considered to be responsible for the low peak hardness obtained for the composites.
Also, other intermetallic particles (such as aluminosilicates and Fe-nch particles) were
observed.
Aluminide (Al,FeNi) particles, which usually occur in AA2618, were detennined to
possess a variety of chernical fomulae. Also, the A1,FeNi phase was determined to be
more consistentiy indexed on the basis a Ctentered monoclinic crystal structure with a
P
= 0.867 nrn; b = 0.900 nm; c = 0.859 nm; and = 83.50" rather than the primitive
monoclinic structure reported in the Literature.
1 would like to thank my supervisor, Dr. S. Yannacopoulos, for his direction and
assistance in this research. 1 would like to thank Duralcan Aluniinurn Company, San
Diego (USA) for the supply of the test materials. Also, I am very grateful for the
criticisms received from members of my supervisory cornmittee. Technical assistance
received from Mr. Phi1 Siminoff, Mr. Tom BonIi (Geology Department), Dr. Asern
Hedayat, and Dr. M. C. Chaturvedi and his research group at the MechanicaI and
Industrial Engineering Department, University of Manitoba, Winnipeg, is highly
appreciated. I am grateful to Dr. S. O. Kasap (EE Department, U of S) for his assistance
with thermal analysis and Dr. Yan Jin (Department of Physics, Carnegie Mellon
University, PA, USA.) for his assistance with crystallographic analysis.
1 would like to thank my colleagues, Mojdeh Radjabi, Nathan Gennan, Ehab Shaheen,
Ali Abedian, and Ray Taheri for many useful discussions. Also, my thanks go to Mr.
Chike Odigboh, Mr. Kenechukwu Ezeike, Mr. Lfeanyi Odigboh, Dr. Cornelius
Muojekwu, Dr. Cosmas Oguejifor, Dr. Jude Uzonna, and other fnends 1 made in
Saskatoon for their friendship, cooperation, and continued encouragement. 1 am
especially gratefuI to Dr. and Mrs. Davidson Oguocha, Dr. and Mrs. Raphael Idem, Dr.
and Mrs. 'Diran Fasina, Dr. and Mrs. Emeka Oguejiofor, Dr. and Mrs. Edwin Annze,
Dr. and Mrs. Adebayo Adams, and Mr. and Mrs. Joseph Jobi for their continued support
and advice.
This work was made possible by the financiai support from the NSERC gants to my
supervisor and the funding 1 received from (i) the Canadian Commonwealth Scholarship
and Fellowship Plan, (ii) Department of Mechanical Engineering (Graduate Teaching
Fellowship) and (iii) School of Graduate Studies (Graduate Service Fellowship). 1 am
very grateful.
May God bless you dl.
My Paren&
and
Priincss Nonye/um Oguocha
TABLE OF CONTENTS
PERMISSION TO USE ....................................................................................................... i
...
ABSTRACT ............................ ................ ...........-.........................................................i.i.
ACKNOWLEDGMENTS. ................................................................................................. iv
DEDICATION .................................................................................................................... v
...................................................................................................
TABLE OF CONTENTS vi
LIST OF TABLES ............................................................................................................. ix
............................................................................................................
LIST OF FIGURES xi
NOMENCLATURE. ....................... ... ..............................................................................x vi
Abbreviations ................................................................................................................ xvi
..
Greek Symbols. ............................................................................................................ xvri
1. INTRODUCTION. ....................................................................................................... 1
1.1 Alurninum Alloy 26 18 ........................................................................................... 2
1.2 Particle-Reinforced Metai Matrix Composites ...................................................... 3
1.3 Objectives .............................................................................................................. 4
2 . LITERATURE REVIEW ...................................*................................................ . ........ 6
2.1 Review of Precipitation Hardening in Alurrîinum Alloys ..................................... 6
2.1.1 Microstnictural Changes in Al-Cu-Mg (kAU)oys . ...................... ... ..... 9
2.2 Fabrication of Particle-Reinforced MMCs ......................................................... 11
........................................................................................
2.2.1 Powder Metallurgy 11
2.2.2 Compocasting. ............................................................................................... 12
2.2.3 SprayFomiing .............................................................................................. 13
2.2.4 XDTMP rocess (Reactive Processing). ........................................................... 14
2.3 Engineering Properties of Particle-Reinforced MMCs ........................................ 16
.........................................................................................................
2.3.1 Stiffness 17
2.3.2 Elongation ..................................................................................................... 18
2.3.3 St rength ......................................................................................................... 2 1
2.3.4 Wear Resistance ............................................................................................ 23
2.4 The Effect of Reinforcement Particles on Precipitation in
Aluminum Alloys ...................... ...................................................................... 23
..,,
2.5 Methods Used for Kinetic Analysis of Precipitation Reactions ........................ .. 25
2.5.1 Kinetics of Isothermal Transformations. .................... .. ................................. 28
2.5.2 Non-Isothermal Analysis .............................................................................. 31
3 . MATERIALS AND EXPEFXMENTAL PROCEDURE ........................................... 35
3.1 Materials ..........................................................~...................................................3 5
3.2 Expenmental Techniques .................................................................................... 36
3.2.1 Hardness Measurements. ....................~........................................................ 4 0
3 .2.2 Differential Scanning Calorimetry ................................................................ 40
3 .2.3 Transmission Electron Microscopy .......................... .... ................................4 1
3.2.4 Scanning Electron Microscopy and Electron Probe Microanalysis .............. 43
3.2.4.1 X-ray Mapping .......................................................................................... 4 5
3.2.4.2 Detennination of Reaction Products .......................... . ............................... 45
4 . RESULTS AND DISCUSSION ......................................................~........................ 46
4.1 Microhardness ...................................................................................................... 46
4.2 SEM and EPMA Results .................................... .... .............................................5 0
4.2.1 The Nature of Alurninide Particles .............................................................. 50
4.2.2 Depletion of Magnesium in the Composite Matrix ...................................... 60
4.2.3 Other htermetallic Phases ............................................................................ 64
4.3 TEM Results ........................................................................................................ 70
4.3.1 Insoluble Particles ................. ............. . ......... ......-.---....-..........7.0.*
4.3.2 Precipitate Phases .......................................................................................... 76
...........................................................
4.3.3 Crystai St mcture of Alurninide Phase 88
.......................................................................................................
4.4 DSC Results '02
....................................................................................
4.4.1 General Description 102
4.4.2 Determination of Kinetic Parameters for Precipitation. ......... ... .............. 108
4.4.2.1 GPB Zone Formation (Peak A) ............................................................... 108
4.4.2.2 GPB Zone Dissolution (Trough B) ...................................................... 120
vii