Table Of ContentE
Materials Research and Engineering
Edited by B. llschner and K. C. Russell
Horst Buhl (Ed.)
Advanced
Aerospace Materials
Springer-Verlag
Berlin Heidelberg New York
London Paris Tokyo
HongKong Barcelona Budapest
Dr. HORST BUHL
DLR, German Aerospace Research Establishment
Institute of Materials Research
Linder Hohe
W-5000 KOin 90/Germany
Series Editors
Prof. BERNHARD ILSCHNER
Poly technique Federale de Lausanne
Laboratoire de Metallurgie Mecanique
MX-D Ecublens Ecole
CH-I0l5 Lausanne/Switzerland
Prof. KENNETH C. RUSSELL
Department of Materials Science and Engineering and
Department of Nuclear Engineering
Room 8-411
Massachusetts Institute ofT echnology
Cambridge, MA 02139/USA
ISBN 978-3-642-50161-6 ISBN 978-3-642-50159-3 (eBook)
DOl 10.1007/978-3-642-50159-3
Library of Congress Cataloging-in-Publication Data
Buhl, Horst
Advanced aerospace materials 1 Horst Buh!.
(Materials researches and engineering)
Includes bibliographical references and index.
ISBN 978-3-642-50161-6
I. Airplanes --Materials. 2. Composite materials.
I. Title. II. Series: Materials research and engineering (Unnumbered)
TL698.B84 1992 629.1--dc20 92-30704
This work is subject to copyrighLAll rights are reserved, whether the whole orpart ofthe material is
concerned, specifically the rights of translation, reprinting, re-use of illustrations, recitation,
broadcasting, reproduction on microfilms orin otherways,and storage in data banks. Duplication
ofthis publication orparts thereofis only permitted under the provisions ofthe German Copyright
Law ofSeptember9, 1965, in its current version and a copyright fee must always be paid. Violations
fall under the prosecution act of the German Copyright Law.
© Springer-Verlag Berlin, Heidelberg 1992
Softcover reprint of the hardcover 1st edition 1992
The use of registered names, trademarks, etc. in this publication does not imply, even in the
absence ofa specific statement, that such names are exempt from the relevant protective laws and
regulations and therefore free for general use.
Typesetting: Camera ready by author
61/3020-543210 - Printed on acid-free paper.
DlR - Institut fur Werkstoff-Forschung
Arbe tsschwerpunkte
• hochfeste lelchlbauwerkstofle lOr Lu!t und Raumlahn
• Hochtemperatur Werks!ofle lOr Antflebe
Werkstofte Akuvlt&ten
Professor Dr. Wolfgang J. G. Bunk
Professor Dr. W.G.J. Bunk, Director of the DLR (German Aerospace
Research Establishment) Institute of Materials Research since 1970,
retires in 1992. With his retirement an epoch of the institute's history
comes to an end, an epoch characterized by expansion in resources,
competence, and size, and national as well as international appreci
ation.
As an expression of their gratitude for his leadership, the scientific
staff of the institute devotes this book to Professor Bunk.
On beha(f of the members of the staff
Horst Buhl
Foreword
Very light, very strong. extremely reliable - aircraft and aerospace engineers are.
and have to be. very demanding partners in the materials community. The results
of their research and development work is not only crucial for one special area
of applications. but can also lead the way to new solutions in many other areas
of advanced technology.
Springer-Verlag and the undersigned editor are pleased to present in this volume.
an overview of the many facets of materials science and technology which have
been the objective of intensive and systematic research work during past decades
in the laboratories of the German Aerospace Research Establishment. Its contents
shows clearly the interrelations between goals defined by the user. fundamentals
provided by the scientists and viable solutions developed by the practical engineer.
The particular personal touch which has been given to this volume by its authors
in dedicating it as a farewell present to Professor Wolfgang Bunk. inspiring sci
entist and director of the DLR Intitute of Materials Research for more than 20
years. has obviously given an added value to this important publication. Surely.
this truly cooperative endeavour will render a valuable service to a large interna
tional community of interested readers. many of them having personal links to the
Institute. its director and its staff.
Lausanne. June 1992 Bernhard I1schner
Preface
During the period 1970 to 1992 the European aircraft industry experienced a big
impetus and a worldwide breakthrough with the successful implementation of the
family of Airbus aircraft. In the area of space launch vehicles. Ariane developed
into an efficient and reliable carrier for satellites. Safe. reliable and durable
materials were the precondition for this success in both cases. Columbus. the
European contribution to the US space station Freedom. as well as the European
efforts to create an autonomous space policy regarding such projects as Hermes
and Sanger, are a big challenge for the materials research community. too.
The authors of this book. my collegues at the Institute of Materials Research of
the German Aerospace Research Establishment. took part in this development
from the beginning. The emphasis of this book. therefore. lies on the research
activities of these authors. It is primarily conceived as a vista into the fascinating
world of aerospace materials and may well serve as an introduction. On the other
hand, its content is always embedded into the context of the international state of
knowledge in materials science, and many topics are dealt with in detail, limited
however by space considerations. A comprehensive bibliography yields access to
the many specialized fields of aerospace materials.
The book is introduced by a visionary overview by W.J.G. Bunk on the present
situation of aerospace materials and perspectives for the future. Thus. the ground
is prepared to allow the reader to examine different aspects of the subject matter.
The structure of the content is, as in many treatments of materials science and
engineering, developed along two axes: First, groups of materials like metals,
ceramics, polymers, and their composites are dealt with. Then properties as well
as suitable test methods and the application related interpretation of test results
form a second guideline. This holds for mechanical properties such as fracture and
fatigue behaviour as well as for corrosion resistance and the field of microstruc
tural and microanalytical techniques. After all, the goal is a cost effective and
reliable aerospace structure, and these properties do not exclusively relate to one
single material.
The book is designed as an introduction to materials research as well as a guide
to anyone who comes in contact with advanced materials. It may be an introduc
tion for graduate students of engineering science into the field of highly developed
lightweight structural and high temperature turbine materials. The comprehensive
survey may also supply materials scientists with information on the actual state
of the art. new materials and test methods and quick answers to problems. as well
as references to more profound information. Also, service engineers, not only from
the aerospace industry, may find valuable details and references.
VIII Preface
I am greatly indebted to my colleages at the Institute of Materials Research, who
contributed to this book and who are listed below:
Braue, W. Braun, R. Bunk, W.GJ.
Doker, H. Dudek, H.-J. Eschweiler, J.
Fritscher, K. Goring, J. Kumpfert, J.
Lehnert, F. Leucht, R. Marci, G.
Nowack, H.I) Peters, M. Peters, P.W.M.
Pleger, R. Ratzer-Scheibe, H.-J. Saruhan, B.
Schneider, H. Schulte, K.2) Schulz, U.
Spiegelberg, M. Staniek, G. Trautmann, K.-H.
Ward, C.H.3) Welpmann, K.
I) now Universitat Gesamthochschule Duisburg
2) now Technische Universitat Hamburg-Harburg
3) now Wright Laboratory, Wright-Patterson AFB, OH, USA
The support of Prof. B. Ilschner, the editor of the Springer Series, "Materials
Research and Development", is gratefully acknowledged. He enabled the publica
tion of this book and supported its preparation with much valuable advice. Special
thanks owe given to Mrs. C. Kotauschek who typed most of the contributions and
to Mrs. S. Giegerich who revised the text regarding the language. Thanks is due
also to the following technical collaborators who were involved in the preparation
of the numerous figures and diagrams: M. Alperth, K. Baumann, H. Hemmnns,
U. Krebber, H. Mettemich, and H. Schurmann.
Cologne, June 1992 Horst Buhl
Contents
1. Situation and Perspectives .................................. 1
2. Metallic Materials and Metal Matrix Composites .................. 21
2.1 Metallic Materials .................................... 21
2.l.l Aluminium Alloys .................................. 21
2.1.1.1 High-Strength Aluminium Alloys ..................... 21
2.1.1.2 Aluminium-Lithium Alloys ......................... 35
2.1.1.3 Powder Metallurgy of Aluminium Alloys ............... 47
2.1.2 Titanium Alloys and Aluminides ........................ 58
2.1.2.1 Titanium Alloys ................................. 58
2.1.2.2 Titanium Aluminides ............................. 73
2.1.3 Superalloys and Coatings ............................. 84
2.1.3.1 S uperalloys .................................... 84
2.1.3.2 High Temperature Corrosion ........................ 87
2.1.3.3 Coatings ...................................... 96
2.2 Metal-Matrix Composites ............................. 108
2.2.1 Metal-Matrix Composites with Aluminium Matrix ........... 108
2.2.2 Fibre Reinforced Aluminium Laminates .................. 118
2.2.3 Titanium Matrix Composites .......................... 124
2.2.4 Interfaces in Metal Matrix Composites ................... 139
3. Ceramic Materials and Ceramic Matrix Composites ............... 153
3.1 Non-Oxide Materials (Silicon Nitride) ..................... 153
3.1.1 Fabrication and Microstructural Development of Non-Oxide
Ceramics (Silicon Nitride) ............................ 154
3.1.2 Silicon Nitride Matrix Composites ...................... 164
3.1.3 Fracture and Fatigue of Non-Oxide Ceramics .............. 177
3.2 Oxide Materials (Mullite) ............................. 189
3.3 Imaging Microstructures of Monolithic Carbons and Carbon/Carbon
Composites in the TEM .............................. 203
4. Polymer Matrix Composites ............................... 219
4.1 Quasi-Static Strength of Polymer Matrix Composites .......... 220
4.2 Fatigue Strength of Polymer Matrix Composites .............. 238
5. Materials Characterization and Life Prediction 246
5.1 Microstructural and Microanalytic Methods ................. 246
5.2 Fatigue and Fracture of Metallic Materials .................. 263
5.2.1 Random Load Fatigue and Life Prediction ................ 263
5.2.2 Physical Reasons for the Existence of L\Kcff ................ 273
5.2.3 Crack Growth Life Prediction ......................... 289
5.3 Special Testing Techniques ............................ 296
x
Contents
5.3.1 Stress Corrosion Testing ............................. 296
5.3.2 Biaxial Testing ................................... 308
5.3.3 Chevron Notched Specimen Testing ..................... 318
Bibliography 327
Abbreviations 360
Index ................................................. 363
Laudatio ............................................... 372
1. Aerospace Materials,
Situation and Perspectives
W.J.G. Bunk
Since aluminium was first used about 1900 as a structural material for the
Zeppelin, this light metal was further developed into a long list of alloys and
properties tailored to fit the needs of aeroplane builders around the world. It seems
to have come to a market saturation because of the advent of carbon fibre rein
forced polymer matrix composites. Titanium and nickel base super alloys dominate
compressor and turbine materials for jet engines. Intermetallics and ceramics may
replace some alloys in the future. From nature engineers have learned to strengthen
a component by particle or fibre reinforcement.
Quite a number of innovative processing techniques emerging from aerospace
material targets have been designed and introduced. It is not surprising to recog
nize materials research and development efforts shifting to some extent from
conventional materials processing companies to more or less integrated aerospace
groups. This may even be more pronounced in the future for quality, safety and
cost reasons. Transfer of advanced aerospace materials and processing technolo
gies to other markets is possible and often wanted, but sometimes problematic
from the economic point of view.
It takes 10 years or more until a new material produced with advanced process
ing technology reaches maturity and full commercialization. This fact is sometimes
difficult to acknowledge by industrial management and governmental funding
agencies. Strategic considerations lead to goals, requirements and limitations.
Safety comes first, followed by performance, and final\y cost of material and
processing net shapes, including recycling: A system's approach.
One notices considerable competition between light metals and carbon fibre
reinforced polymers (PMC). There are different extrapolation curves published in
the literature concerning the balance of light metals and PMCs in airframe com
ponents.
One of the important requirements for aerospace materials is resistance to ele
vated temperatures. Figure 1.1 summarizes the experience of the aerospace
industry.
For aerospace materials and components considerable development activity is
required in order to correctly select and ratify their suitability. It is necessary to
demonstrate performance achievement and acceptable manufacturing costs. Influ
encing factors include environmental conditions, ease of processing and ability to
inspect and repair parts, to name just a few.
