Processing and properties of high performance 7075 Al and AZ91 Mg powder metallurgy alloys

149 Pages·2015·8.8 MB·English

SUMMARY
PROCESSING AND PROPERTIES OF HIGH PERFORMANCE
2014
7075 AL AND AZ91 MG POWDER METALLURGY ALLOYS
Aluminum (Al) and magnesium (Mg) alloys have received considerable
attention over the past decades as potential materials of choice to achieve
significant weight savings. Although the market for Al and Mg products
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continuestogrow,manyopportunitiesremainuntappedbecauseofthelow LI AN
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stiffnessandstrengthofAlandMgalloysincomparisonwithferrousalloys D G
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andsomeotherstructuralmaterials.Ontheotherhand,grainrefinementis MAAL
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consideredaneffectivewaytoincreasethestrengthofmetallicmaterials.In ARI
recent years, high-energy milling has been widely exploited for the HA
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production of nanostructured materials, and grain sizes with nanometer MB
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bymechanicalalloyinghasbeenthesubjectofmanystudies,studiesonthe AL
ML Doctoral Thesis
high-energymillingofMgalloysarescarce.Itshouldalsobeconsideredthat A
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to be suitable for structural applications, the nanocrystalline Al and Mg OY
FG Processing and properties of
powders produced by mechanical alloying should then be consolidated to RR
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bulk materials. The consolidation route can have significant effects on the PL high performance 7075 Al and AZ91 Mg
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microstructure and mechanical properties of the processed bulk product. GT
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However, to the best of our knowledge, there are no systematic studies HM
comparingtheeffectsofdifferentconsolidationroutesonthemicrostructure OF R
and mechanical properties of the bulk products processed from S DE
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mechanicallyalloyedAlandMgpowders. T
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The research work presented in this thesis was aimed to produce high- O
RM Director: Dr. José Manuel Torralba Castelló
performanceAlandMgalloysviapowdermetallurgyusingdifferentpowder P1
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processing techniques and consolidation routes and to understand the Z
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effectsofconsolidationrouteanditsprocessvariablesthroughundertaking G AD
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acomprehensivestudyofthemicrostructuralandmechanicalcharacteristics N
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TESIS DOCTORAL

Processing and properties of high performance
7075 Al and AZ91 Mg powder metallurgy alloys

Author:
Mohammad Ali Jabbari Taleghani

Director:
Dr. José Manuel Torralba Castelló

A Dissertation submitted for the degree of Doctor of Philosophy at the
Department of Materials Science and Engineering
and Chemical Engineering

Universidad Carlos III de Madrid
November 2014

TESIS DOCTORAL

Processing and properties of high performance 7075 Al
and AZ91 Mg powder metallurgy alloys

Autor: Mohammad Ali Jabbari Taleghani

Director: Dr. José Manuel Torralba Castelló

FIRMA DEL TRIBUNAL CALIFICADOR
Firma
Presidente: Dr. Elena Gordo Odériz
Vocal: Dr. Leandro Bolzoni
Secretario: Dr. Javier Hidalgo García

Calificación:

Leganés, 26 de Noviembre de 2014

TO MY FAMILY
TO ALL MY BELOVED FRIENDS
TO JOSE MANUEL

Acknowledgements
Looking back at my PhD years at the Department of Materials Science and Engineering
of Universidad Carlos III de Madrid (UC3M), I feel that things have run very smoothly for
me. I owe this to all my dearest Spanish friends and colleagues at the Grupo de Tecnología de
Polvos (GTP). Chicos, muchas gracias! Nunca olvidaré su amabilidad y Amistad.
My special thanks go to my supervisor, prof. Jose Manuel Torralba, who has been an
endless source of knowledge, ideas, and enthusiasm. He has given me the chance to stand
where I am right now leading me all this time through the way, as a mentor with his
comments, remarks, and advices. Jose, I consider you as one of the brightest people I have
ever met, and working with you has been a great privilege and honor. You are much more
than a supervisor to your university family.
I am also grateful to my working group from Grupo de Tecnología de Polvos (GTP): Dr.
Elisa María Ruiz Navas, Dr. Elena Gordo, and Dr. Mónica Campos, Dr. Mª Eugenia Rabanal
Jiménez, and Dr. Antonia Jiménez Morales for being so warm and friendly and for providing
excellent scientific and technical assistance whenever needed. I would also like to express my
gratitude to Dr. Cristina Moral Gil, Mr. Juan Carlos Nieto Sierra, and Mr. Luis Alberto López
Muñoz, who can fix all sort of complicated technical problems in the blink of an eye.
I would like to thank all the members (past and present) of IMDEA Materials Institute
for creating a very pleasant working environment. The friendly, supportive atmosphere
inherent to the whole institute contributed to the final outcome of my studies, not only during
the working hours at the institute but also during the free time. To all of them, I am truly
grateful. Besides, I sincerely appreciate all the scientific and technical help received from Dr.
Ilchat Sabirov, Dr. Srdjan Milenkovic, Dr. Teresa Pérez Prado, and Dr. Jon Molina. These
guys are just great. I would also like to thank prof. Javier Llorca, the president of IMDEA
Materials institute, for his constant and sincere follow-up of my progress.
I acknowledge gratefully the provision of financial support for the research work
described in this thesis by IMDEA Materials Institute. I should also thank the Comunidad de
Madrid for their financial support of this work through the ESTRUMAT Grant
#S2009/MAT-1585.
I sincerely thank all my dear friends in Spain and Iran. They have continuously helped
me throughout my PhD thesis as well as my personal life.
I am deeply thankful to my beloved mum and dad, Monir and Bijan, for always being
there for me and believing in me. I am also very grateful to my sister and brother, Behnaz and
Behshad for their endless love and support.

TABLE OF CONTENTS

ABSTRACT .................................................................................................................... 1
RESUMEN ...................................................................................................................... 3
PREFACE ....................................................................................................................... 5
CHAPTER 1 MOTIVATION AND OBJECTIVES ........................................................ 11
1.1 Introduction ..................................................................................................... 11
1.2 Research objectives ........................................................................................ 12
References............................................................................................................ 13
CHAPTER 2 LITERATURE REVIEW ......................................................................... 17
2.1 Al and Al Alloys ............................................................................................... 17
2.1.1 7xxx series Al Alloys ................................................................................ 17
2.2 Mg and Mg Alloys ........................................................................................... 18
2.2.1 AZ Mg Alloys............................................................................................. 19
2.3 Fine-Grained and Nanocrystalline Materials ................................................... 19
2.4 Powder Metallurgy (PM) of Al and Mg............................................................. 21
2.4.1 Powder Metallurgy of Al ............................................................................ 22
2.4.2 Powder Metallurgy of Mg .......................................................................... 23
2.4.3 The PM Processing Routes ...................................................................... 24
2.5 Powder Production .......................................................................................... 25
2.5.1 Atomization ............................................................................................... 25
2.5.2 Mechanical Grinding ................................................................................. 26
2.5.3 Mechanical Alloying .................................................................................. 26
2.6 Powder Compaction. ....................................................................................... 28
2.7 Sintering. ......................................................................................................... 30
2.7.1 Solid State Sintering. ................................................................................ 30