**6. References**

254 Recent Trends in Processing and Degradation of Aluminium Alloys

demonstrated that water can trigger cerium dibuthylphosphate (Ce(dbp)3) release into an epoxy matrix resulting in improved adhesion and resistance to filiform corrosion attack

In terms of delivery systems, hard capsules, which have been used in polymer healing (Dry 1996; White, Sottos et al. 2001; Mookhoek, Mayo et al. 2010) need to be smaller for paint systems particularly in the aerospace industry where coatings are typically 20 μm or less (Yin, Rong et al. 2007; Fischer 2010; Mookhoek, Mayo et al. 2010) (Hughes, 2010). In polymer applications, capsules up to a few hundred microns can be accommodated (Yin, Rong et al. 2007; Wu, Meure et al. 2008; Tedim, Poznyak et al. 2010). The concept of encapsulation has already been successfully applied to protective organic coatings under different concepts: i) liquids filling completely the void created by the damage by adopting a bi-component systems where one component is encapsulated and the other distributed in the matrix (Cho, White et al. 2009), or single based components with water reactive oils like linseed and tung oils (Suryanarayana, Rao et al. 2008; Samadzadeh, Boura et al. 2010)and ii) liquids (i.e. silyl esters) forming a hydrophobic and highly adhesive layer covering the metallic surface by reaction with the underlying metal and the humidity in air (Garcia, Fischer et al. 2011). One adaption for capsules is to increase the volume of self healing material by manufacturing rods instead of spheres. Rods with the same cross-sections as spheres can deliver larger volumes of material (Bon, Mookhoek et al. 2007; Mookhoek, Fischer et al. 2009). For inhibitors, their role is to prevent a surface reaction (corrosion) and therefore, the volume of material required is much smaller than that required to actually fill the defect. Consequently, there has been considerable effort looking at "nano-containers" (Voevodin,

through interfacial modification (Mardel, Garcia et al.).

Balbyshev et al. 2003; Raps, Hack et al. 2009; Tedim, Poznyak et al. 2010).

Simoes et al. 2006).

**5. Conclusions** 

Water is the most obvious trigger since it can permeate most polymers. pH variations are more specific and respond to the pH excursions that occur in corrosion reactions and by an understanding reactions that occur at different sites in the alloy microstructure. The presence of chloride ions (and other anions) within the coating can be used as specific triggers for the release of corrosion inhibitors and uptake of corrodents using anion exchange materials, such as layered double hydroxides (e.g. hydrotalcites) (Tedim, Poznyak et al. 2010) (Bohm, McMurray et al. 2001; Buchheit, Guan et al. 2003; Williams and McMurray 2003; Zheludkevich, Salvado et al. 2005; Mahajanarn and Buchheit 2008). In this context hydrotalcites have been loaded with vanadate, chromate, nitrate and carbonate which exchange for chloride ions and prevent interfacial damage (Bohm, McMurray et al. 2001; Williams and McMurray 2003; Mahajanarn and Buchheit 2008). The incorporation of Mg particles into paint acts as sacrificial anodes to protect Al alloys and steels (Battocchi,

The broad range of microstrucutral characteristics associated with the high strength Alalloys have been examined in detail. Perhaps the most attention has been paid to the AA2024-T4 legacy alloy where the microstructure is complicated by the broad compositional variation of second phases, particularly the constituent particles. The role of these features on corrosion has been described and areas where the role of the microstructure is still not clearly understood have been identified and discussed. In the light of a continually emerging understanding of alloy microstructure some general principles of

inhibitor design and incorporation into paints systems have been explored.


High Strength Al-Alloys: Microstructure, Corrosion and Principles of Protection 257

Furman, S. A., F. H. Scholes, et al. (2006). "Corrosion in artificial defects. II. Chromate

Gao, M., C. R. Feng, et al. (1998). "An analytical electron microscopy study of constituent

Transactions a-Physical Metallurgy and Materials Science 29(4): 1145-1151. Garcia-Vergara, S., F. Colin, et al. (2004). "Effect of copper enrichment on the electrochemical

Garcia, S. J., H. R. Fischer, et al. (2011). "Self-healing anticorrosive organic coating based on

García, S. J., Mol, J.M.C., Muster, T.H., Hughes, A.E., Mardel, J., Miller, T., Markely, T.,

Glenn, A. M., T. H. Muster, et al. (2011). "Corrosion of AA2024-T3 Part III: Propagation."

Guillaumin, V. and G. Mankowski (1999). "Localized corrosion of 2024 T351 aluminium

Habazaki, H., K. Shimizu, et al. (1997). "Nanoscale enrichments of substrate elements in the

Hahn, G. T. and A. R. Rosenfield (1975). "Metallurgical Factors Affecting Fracture Toughness of Aluminum-Alloys." Metallurgical Transactions A 6(4): 653-668.

Harvey, T. G., A. E. Hughes, et al. (2008). "Non-chromate deoxidation of AA2024-T3:

Ho, D., N. Brack, et al. (2006). "Cerium dibutylphosphate as a corrosion inhibitor for

Hughes, A. E., A. Boag, et al. (2011). "Corrosion of AA2024-T3 Part II Co-operative

Hughes, A. E., A. Boag, et al. (2006). Statistical Approach to Determine Spatial and

Hughes, A. E., B. Hinton, et al. (2007). "Airlife - Towards a fleet management tool for

corrosion damage." Corrosion Reviews 25(3-4): 275-293. Hughes, A. E., C. MacRae, et al. (2010). Surface Interface Analysis 42: 334-338.

Hatch , J. E. (1984). Aluminium: Porperties and Physical Metallurgy, ASM International. Hinton, B. R. W., N. Dubrule, et al. (2006). Raman, EDS and SEM studies of the interaction of

Sodium bromate-nitric acid (20-60 degrees C)." Applied Surface Science 254(11):

corrosion inhibitor Ce(dbp)3 with AA2024-T3. 4th International Symposium on

AA2024-T3 aluminum alloys." Journal of the Electrochemical Society 153(9): B392-

Elemental Correlations of Corrosion Sites on Al-Alloys. Aluminium Surface Science and Technology Conference Beaune, France, ATB Metallurgie, 45 (1-4): 551-556. Hughes, A. E., Cole, I.S., Muster, T.M. and Varley, R.J. (2010). "Combining Green and Self

Healing for a new Generation of Coatings for Metal Protection." Nature Asia

alloy in chloride media." Corrosion Science 41(3): 421-438.

growth of thin oxide films." Corrosion Science 39(4): 731-737.

Harlow, D. G., M. Z. Wang, et al. (2006). Metall. mat. Trans A 37A: 3367-3373.

Aluminium Surface Science and Technology. Beaune, France.

corrosion." Corrosion Science 53(1): 27-39.

Materials 2(4): 143-151.

particles in commercial 7075-T6 and 2024-T3 alloys." Metallurgical and Materials

potential of binary Al-Cu alloys." Journal of the Electrochemical Society 151(1): B16-

an encapsulated water reactive silyl ester: Synthesis and proof of concept." Progress

Terryn, H., de Wit, J.H.W. (2011). Advances in the Selection and use of Rare-Earth-Based Inhibitors for Self Healing Organic Coatings, Accepted for publication in Self-Healing Properties of New Surface Treatments. Green Inhibitors. L. Fedrizzi,

reactions." Corrosion Science 48(7): 1827-1847.

in Organic Coatings 70(2-3): 142-149.

EFC-Maney Publishing. 58.

Corrosion Science 53(1): 40-50.

B21.

3562-3575.

B401.


Buchheit, R. G. (1995). "A Compilation of Corrosion Potentials Reported for Intermetallic

Buchheit, R. G., R. P. Grant, et al. (1997). "Local dissolution phenomena associated with S

Buchheit, R. G., H. Guan, et al. (2003). "Active corrosion protection and corrosion sensing in chromate-free organic coatings." Progress in Organic Coatings 47(3-4): 174-182. Buchheit, R. G., Hughes, A.E. (2003). Chromate and Chromate-Free Coatings. Corrosion:

Buchheit, R. G., M. A. Martinez, et al. (2000). "Evidence for Cu ion formation by dissolution

Cavanaugh, M. K., R. G. Buchheit, et al. (2010). "Modeling the environmental dependence of pit growth using neural network approaches." Corrosion Science 52(9): 3070-3077.

Chen, G. S., M. Gao, et al. (1996). "Microconstituent-induced pitting corrosion in aluminum

Cho, S. H., S. R. White, et al. (2009). "Self-Healing Polymer Coatings." Advanced Materials

Das, S. K. (2006). "Designing Aluminium Alloys for a Recycle-Friendly World." Light Metal

Davies, J. R. (1999). Corrosion of Aluminium and Aluminium Alloys. Columbus, OH, ASM

Deacon, G. B., M. Forsyth, et al. (2009). "Synthesis and Characterisation of Rare Earth

Dry, C. (1996). "Procedures developed for self-repair of polymer matrix composite

Du, Y. J., M. Damron, et al. (2001). "Inorganic/organic hybrid coatings for aircraft aluminum

Evans, U. R. (1971). "Inhibition, Passivity and Resistance. A Review of Acceptable

Fishkis, M. and J. C. Lin (1997). "Formation and evolution of a subsurface layer in a

Forsyth, M., T. Markley, et al. (2008). "Inhibition of corrosion on AA2024-T3 by new

Frankel, G. S. (1998). "Pitting corrosion of metals - A review of the critical factors." Journal of

environmentally friendly rare earth organophosphate compounds." Corrosion

Complexes Supported by para-Substituted Cinnamate Ligands." Zeitschrift Fur

Cawley, N. R. and D. G. Harlow (1996). Journal of Material Science 31: 5127-5134.

Anorganische Und Allgemeine Chemie 635(6-7): 833-839.

alloy substrates." Progress in Organic Coatings 41(4): 226-232.

Engelberg, D. L. (2010). Shreir's Corrosion. R. J.A. Amsterdam, Elsevier.

Mechanisms." Electrochimica Acta 16(11): 1825-1840.

metalworking process." Wear 206(1-2): 156-170.

the Electrochemical Society 145(6): 2186-2198.

Fischer, H. R. (2010). natural Science 2: 873-901.

materials." Composite Structures 35(3): 263-269.

Electrochemical Society 144(8): 2621-2628.

ASM International. 13A: 720 -735.

alloy 2024-T3." Corrosion 52(1): 8-15.

3996.

189-217.

21(6): 645-+.

International.

64(3): 191-197.

Age June.

Phases in Aluminum-Alloys." Journal of the Electrochemical Society 142(11): 3994-

phase (Al2CuMg) particles in aluminum alloy 2024-T3." Journal of the

Fundamentals, Testing and Protection. C. Moosbrugger. Mterials Park, Oh, USA,

and dealloying the Al2CuMg intermetallic compound in rotating ring-disk collection experiments." Journal of the Electrochemical Society 147(1): 119-124. Carney, T. J., P. Tsakiropoulos, et al. (1990). "Oxidation and Surface Segregation in Rapidly

Solidified Al-Alloy Powders." International Journal of Rapid Solidification 5(2-3):


High Strength Al-Alloys: Microstructure, Corrosion and Principles of Protection 259

Liao, C. M., J. M. Olive, et al. (1998). "In-situ monitoring of pitting corrosion in aluminum

Liu, Y., M. F. Frolish, et al. (2010). "Evolution of near-surface deformed layers during hot

Liu, Y., A. Laurino, et al. (2010). "Corrosion behaviour of mechanically polished AA7075-T6

Liu, Y., X. Zhou, et al. (2007). "Precipitation in an AA6111 aluminium alloy and cosmetic

Mahajanarn, S. P. V. and R. G. Buchheit (2008). "Characterization of inhibitor release from

Mardel, J., S. J. Garcia, et al. (2011). "The characterisation and performance of Ce(dbp)3 inhibited epoxy coatings." Progress in Organic Coatings 70(2-3): 91-101. Markley, T. A., M. Forsyth, et al. (2007). "Corrosion protection of AA2024-T3 using rare earth

Markley, T. A., A. E. Hughes, et al. (2007). "Influence of praseodymium - Synergistic

Mazurkiewicz, B. and A. Piotrowski (1983). "The Electrochemical-Behavior of the Al2cu

Meng, Q. J. and G. S. Frankel (2004). The effect of Cu content on the localized corrosion

Mol, J. M. C., A. E. Hughes, et al. (2004). "A morphological study of filiform corrosive attack

Mookhoek, S. D., H. R. Fischer, et al. (2009). "A numerical study into the effects of elongated

Mookhoek, S. D., S. C. Mayo, et al. (2010). "Applying SEM-Based X-ray Microtomography to

Muster, T. H., Hughes, A.E., Thompson. G.E. (2009). Cu Distributions in Aluminium Alloys.

Newman, R. C. and K. Sieradzki (1994). "Metallic Corrosion." Science 263(5154): 1708-1709. Nisancioglu, K. S., O., Yu, Y., Nordlien, Y.K. (2004). 55th Annula Meeting of the

Osborne, J. H., K. Y. Blohowiak, et al. (2001). "Testing and evaluation of nonchromated

Pan, X., J. E. Morral, et al. (2010). "Predicting the Q-Phase in Al-Cu-Mg-Si Alloys." Journal of

Park, J. O., C.-H. Paik, et al., Eds. (1996). Critical Factors in Localised Corrosion II., The

International Society of Electrochemistry, Thessaloniki.

Phase Equilibria and Diffusion 31(2): 144-148.

Electrochemical Society, Pennington, NJ.

G. Buchheit, R. G. Kelly, N. A. Missert and B. A. Shaw. 2003: 62-81.

aluminium alloy." Surface And Interface Analysis 42(4): 185-188.

Luo, C., Hughes, A.E., Zhou X., Thompson G.E. (to be published). Corrosion Science.

hydrotalcite-pigmented epoxy coatings." Corrosion 64(3): 230-240. Mao, Y., A. M. Gokhale, et al. (2006). Computational Materials Science 37: 543-556.

diphenyl phosphates." Electrochimica Acta 52(12): 4024-4031.

Electrochemical and Solid State Letters 10(12): C72-C75.

Intermetallic Compound." Corrosion Science 23(7): 697-&.

rolling of AA3104 aluminium alloy." Surface And Interface Analysis 42(4): 180-184.

Zn-Al- V10O28 (6-) hydrotalcite pigments and corrosion protection from

corrosion inhibition in mixed rare-earth diphenyl phosphate systems."

resistance of AA7xxx-T6 alloys. Corrosion and Protection of Light Metal Alloys. R.

on chromated and alkaline-cleaned AA2024-T351 aluminium alloy." Corrosion

capsules on the healing efficiency of liquid-based systems." Computational

Observe Self-Healing in Solvent Encapsulated Thermoplastic Materials." Advanced

coating systems for aerospace applications." Progress in Organic Coatings 41(4):

alloy 2024." Corrosion 54(6): 451-458.

corrosion." Acta Materialia 55(1): 353-360.

Science 46(5): 1201-1224.

217-225.

Materials Science 47(2): 506-511.

Engineering Materials 12(3): 228-234.

New York, Nova Science Publishers.


Hughes, A. E., J. M. C. Mol, et al. (2005). "A morphological study of filiform corrosive attack on cerated AA2024-T351 aluminium alloy." Corrosion Science 47(1): 107-124.

Hunter, M. S. F., G.R., Robinson, D.L. (1963). 2nd International Conference on Metallic

Ilevbare, G. O., O. Schneider, et al. (2004). Journal of Electrochemical Society 151: B453-B464. Ilevbare, G. O., O. Schneider, et al. (2004). "In situ confocal laser scanning microscopy of AA

Juffs, L. (2002). Investigation of Corrosion Coating Deposition on Microscopic and

Juffs, L., A. E. Hughes, et al. (2002). "The use of macroscopic modelling of intermetallic

Juffs, L., A. E. Hughes, et al. (2001). "The use of macroscopic modelling of intermetallic

Jung, D. Y., I. Dumler, et al. (1985). "Electronmicroscopic Examination of Corroded

Kendig, M. W. and R. G. Buchheit (2003). "Corrosion inhibition of aluminum and aluminum

Khramov, A. N., N. N. Voevodin, et al. (2004). "Hybrid organo-ceramic corrosion protection

Kovarik, L., M. K. Miller, et al. (2006). "Origin of the modified orientation relationship for

Lacroix, L., L. Ressier, et al. (2008). "Combination of AFM, SKPFM, and SIMS to study the

Lacroix, L., L. Ressier, et al. (2008). "Statistical study of the corrosion behavior of Al2CuMg

Leth-Olsen, H., J. H. Nordlien, et al. (1997). "Formation of Nanocrystalline Surface Layers by

Leth-Olsen, H., J. H. Nordlien, et al. (1998). "Filiform corrosion of aluminium sheet. III. Microstructure of reactive surfaces." Corrosion Science 40(12): 2051-2063.

S(S'')-phase in Al-Mg-Cu alloys." Acta Materialia 54(7): 1731-1740.

Knight, S. P. (2003). "A review of HEat Treatments." Australasian Corrosion Association. Kolics, A., A. S. Besing, et al. (2001). "Interaction of chromate ions with surface intermetallics

2024-T3 corrosion metrology - I. Localized corrosion of particles." Journal of the

Macroscopic Intermetallic Phases of Aluminium Alloys. Melbourne, RMIT. Master

phases in aluminium alloys in the study of ferricyanide accelerated chromate

phases in aluminium alloys in the study of ferricyanide accelerated chromate

Aluminum-Copper Alloy Foils." Journal of the Electrochemical Society 132(10):

alloys by soluble chromates, chromate coatings, and chromate-free coatings."

coatings with encapsulated organic corrosion inhibitors." Thin Solid Films 447: 549-

on aluminum alloy 2024-T3 in NaCl solutions." Journal of the Electrochemical

corrosion behavior of S-phase particles in AA2024-T351." Journal of the

intermetallics in AA2024-T351 by SKPFM." Journal of the Electrochemical Society

Annealing and Their Role in Filiform Corrosion of Aluminum Sheet." Journal of the

Hughes, A. E., T. H. Muster, et al. (2010). Corrosion Science Accepted. Hughes, A. E., N. Wilson, et al. (2009). Corrosion Science 51: 1565-1568.

conversion coatings." Corrosion Science 44(8): 1755-1781.

Electrochemical Society 151(8): B453-B464.

conversion coatings." Micron 32(8): 777-787.

Electrochemical Society 155(4): C131-C137.

Electrochemical Society 144(7): L196-L197.

Corrosion: 66.

of Science.

2308-2312.

557.

Corrosion 59(5): 379-400.

Society 148(8): B322-B331.

155(1): C8-C15.


High Strength Al-Alloys: Microstructure, Corrosion and Principles of Protection 261

Seri, O. (1994). "The Effect of Nacl Concentration on the Corrosion Behavior of Aluminum-

Sieradzki, K. (1993). "Curvature Effects in Alloy Dissolution." Journal of the Electrochemical

Sinko, J. (2001). "Challenges of chromate inhibitor pigments replacement in organic

Souto, R. M., Y. González-García, et al. (2010). "Examination of organic coatings on metallic

Sprowls, D. O. (1978). "High Strength Aluminium Alloys with Improved Resistance to Corrosion and Stress Corrosion Cracking." Aluminium 54(6): 214 - 217. Suryanarayana, C., K. C. Rao, et al. (2008). "Preparation and characterization of

Suter, T., Alkire, R.C. (2001). "Microelectrochemical Studies of Pit Initiation at Single Inclusions in Al 2024-T3." jJournal of the Electrochemical Society 148(1): B36-B42. Taylor, S. R. and B. D. Chambers (2008). "Identification and characterization of nonchromate

Tedim, J., S. K. Poznyak, et al. (2010). "Enhancement of Active Corrosion Protection via

Trueman, A. R. (2005). "Determining the probability of stable pit initiation on aluminium

Twite, R. L. and G. P. Bierwagen (1998). "Review of Alternatives to Chromate for Corrosion

Voevodin, N. N., V. N. Balbyshev, et al. (2003). "Nanostructured coatings approach for corrosion protection." Progress in Organic Coatings 47(3-4): 416-423. Vukmirovic, M. B., N. Dimitrov, et al. (2002). "Dealloying and corrosion of Al alloy 2024-T3."

Wadeson, D. A., X. Zhou, et al. (2006). "Corrosion behaviour of friction stir welded AA7108

Wei, R. P., C. M. Liao, et al. (1998). "A transmission electron microscopy study of

White, P. A., A. E. Hughes, et al. (2009). "High-throughput channel arrays for inhibitor testing: Proof of concept for AA2024-T3." Corrosion Science 51(10): 2279-2290. White, S. R., N. R. Sottos, et al. (2001). "Autonomic healing of polymer composites." Nature

constituent-particle-induced corrosion in 7075-T6 and 2024-T3 aluminum alloys." Metallurgical and Materials Transactions a-Physical Metallurgy and Materials

Journal of the Electrochemical Society 149(9): B428-B439.

T79 aluminium alloy." Corrosion Science 48(4): 887-897.

substrates by scanning electrochemical microscopy in feedback mode: Revealing the early stages of coating breakdown in corrosive environments." Corrosion

microcapsules containing linseed oil and its use in self-healing coatings." Progress

corrosion inhibitor synergies using high-throughput methods." Corrosion 64(3):

Combination of Inhibitor-Loaded Nanocontainers." Acs Applied Materials &

alloys using potentiostatic electrochemical measurements." Corrosion Science 47(9):

Protection of Aluminum Aerospace Alloys." Progress in Organic Coatings 33(2): 91-

Containing Iron." Corrosion Science 36(10): 1789-&.

coatings." Progress in Organic Coatings 42(3-4): 267-282.

Society 140(10): 2868-2872.

Science 52(3): 748-753.

255-270.

2240-2256.

100.

in Organic Coatings 63(1): 72-78.

Interfaces 2(5): 1528-1535.

Science 29(4): 1153-1160.

409(6822): 794-797.

Thompson, G. E. a. Z. X. (2010). Mater. World 18: 26-27.

Park, J. O., C.-H. Paik, et al. (1999). Journal of the Electrochemical Society 146: 517-523.


Plassart, G., Aucouturier, M. (2000). 2nd International Conference on Aluminium Surface

Poelman, M., M. G. Olivier, et al. (2005). "Electrochemical study of different ageing tests for

Pride, S. T., J. R. Scully, et al. (1994). "Metastable Pitting of Aluminum and Criteria for the

Pryor, M. J. and J. C. Fister (1984). "The Mechanism of Dealloying of Copper Solid-Solutions and Intermetallic Phases." Journal of the Electrochemical Society 131(6): 1230-1235.

Ralston, K. D., N. Birbilis, et al. (2010). "The effect of precipitate size on the yield strength-

Raps, D., T. Hack, et al. (2009). "Electrochemical study of inhibitor-containing organicinorganic hybrid coatings on AA2024." Corrosion Science 51(5): 1012-1021. Raviprasad, K., C. R. Hutchinson, et al. (2003). "Precipitation processes in an Al-2.5Cu-1.5Mg (wt. %) alloy microalloyed with Ag and Si." Acta Materialia 51(17): 5037-5050. Samadzadeh, M., S. H. Boura, et al. (2010). "A review on self-healing coatings based on

Sasaki, K., P. W. Levy, et al. (2002). "Electrochemical noise during pitting corrosion of

Scamans, G. M., Afseth, A., Thompson, G.E., Zhou X (2000). 2 nd International Conference

Scamans, G. M., M. F. Frolish, et al. (2010). "The ubiquitous Beilby layer on aluminium

Schneider, O., G. O. Ilevbare, et al. (2004). Journal of Electrochemical Society 151(B\$65-B472). Schneider, O., G. O. Ilevbare, et al. (2004). "In situ confocal laser scanning microscopy of AA

Scholes, F. H., S. A. Furman, et al. (2006). "Chromate leaching from inhibited primers - Part I. Characterisation of leaching." Progress in Organic Coatings 56(1): 23-32. Scholes, F. H., A. E. Hughes, et al. (2009). "Interaction of Ce(dbp)(3) with surface of

Scully, J. R., T. O. Knight, et al. (1993). "Electrochemical Characteristics of the Al2cu, Al3ta

Searles, J. L., P. I. Gouma, et al. (2001). "Stress corrosion cracking of sensitized AA5083 (Al-

micro/nanocapsules." Progress in Organic Coatings 68(3): 159-164.

on Aluminium Surface Science and Technology. Manchester: 9 - 15.

surfaces." Surface And Interface Analysis 42(4): 175-179.

Corrosion Engineering Science and Technology 44(6): 416-424.

Electrochemical Society 151(8): B465-B472.

Al-Alloys." Corrosion Science 35(1-4): 185-195.

and Materials Science 32(11): 2859-2867.

Polmear, I. J. (1995). Light Allopys: Metallurgy of the Light Metals. London, Arnold. Polmear, I. J. (2004). "A Century of Age Hardening." Materials Forum 28: 1 - 14.

Magnesium, Manganese, Iron and Silicon." The Journal of the Institute of Metals 77:

the evaluation of a cataphoretic epoxy primer on aluminium." Progress in Organic

Transition to Stable Pit Growth." Journal of the Electrochemical Society 141(11):

pitting corrosion correlation in Al-Cu-Mg alloys." Acta Materialia 58(18): 5941-5948.

aluminum in chloride environments." Electrochemical and Solid State Letters 5(8):

2024-T3 corrosion metrology - II. Trench formation around particles." Journal of the

aluminium alloy 2024-T3 using macroscopic models of intermetallic phases."

And Al3zr Intermetallic Phases and Their Relevancy to the Localized Corrosion of

4.5Mg-1.0Mn)." Metallurgical and Materials Transactions a-Physical Metallurgy

Park, J. O., C.-H. Paik, et al. (1999). Journal of the Electrochemical Society 146: 517-523. Phragmen, G. (1950). "On the Phases Occurring in Alloys of Aluminium with Copper,

Science and Technology. Manchester: 29 - 35.

489-553.

3028-3040.

B25-B27.

Coatings 54(1): 55-62.


**11** 

Andrzej Pawełek

*Poland* 

*Polish Academy of Sciences, Kraków,* 

**Mechanical Behavior and** 

**Plastic Instabilities of Compressed Al Metals** 

The aim of the present chapter has been to substantiate and explain the relation among the behavior of acoustic emission (AE) parameters, the course of external load, evolution of microstructure and the dislocation mechanisms of slip and the localization of deformation connected with twinning, formation of slip and shear bands. The problem is of fundamental meaning, when qualitative and quantitative relations between the rate of AE events, amplitude and energy of AE signals and other AE descriptors in relation to micro-processes

It is commonly believed that twinning is the most efficient source of acoustic emission (Bidlingmaier et al., 1999; Boiko, 1973; El-Danaf et al., 1999; Heiple & Carpenter, 1987; Tanaka & Horiuchi, 1975) due to fast release of great amount of elastic energy. It is connected with the fact that the velocity of twinning dislocations is higher than this of slip dislocations (Boiko, 1973), which results in the increase of contribution of accelerating effects

One of the first AE investigations concerned the tensile test of titanium and its alloys (Tanaka & Horiuchi, 1975), in which it was established, that the AE activity in Ti was bound with twinning from the beginning, while in Ti alloys the AE impulses from twinning appeared after a high degree of deformation. During compression of the γ-TiAl alloy, AE sources were identified as generally coming from slip, twinning and the propagation of microcracks. It was reported, however, that the detailed mechanisms by which moving dislocations create elastic waves are still not fully understood (Bidlingmaier et al., 1999). Moreover, the problem of twinning in Al has still remained controversial. It is believed quite commonly, that at least in simple uniaxial strain state, like in a tensile test, twins do not appear in Al. One of the aim of this chapter is to demonstrate, that there are numerous proofs, that in a complex strain state, which occurs in the channel-die compression of single

The reasons for undertaking such a research are numerous. At first, there is lack in literature of the experimental data on the AE behavior during channel-die compression of single

Al crystals at temperature of liquid nitrogen the twinning processes do occur.

**1. Introduction** 

occurring in a material are to be discussed.

in the recorded AE impulses.

**and Alloys Investigated with Intensive** 

**Strain and Acoustic Emission Methods** 

*Aleksander Krupkowski Institute of Metallurgy and Materials Science* 

