WWW.DISSERTATION.XLIBX.INFO
FREE ELECTRONIC LIBRARY - Dissertations, online materials
 
<< HOME
CONTACTS



Pages:     | 1 | 2 || 4 | 5 |   ...   | 19 |

«STRUCTURE AND PROPERTIES OF ELECTRODEPOSITED NANOCRYSTALLINE NI AND NI-FE ALLOY CONTINUOUS FOILS by Jason Derek Giallonardo A thesis submitted in ...»

-- [ Page 3 ] --

In general, there are still some characteristics and properties of these materials which require an advanced understanding. Microstructural studies on electrodeposited nanocrystalline materials have often been limited to the X-ray diffraction (XRD) and conventional transmission electron microscopy (TEM) methods. Only a few studies have used high-resolution transmission electron microscopy (HR-TEM) with a narrow scope to examine the microstructure of electrodeposited nanocrystalline materials. For example, Mehta et al. (1995) reported the presence of low angle grain boundaries and twin boundaries in electrodeposited nanocrystalline Ni and Ni-1.2wt.%P. However, the grain boundary characteristics were not studied in great detail. Mehta et al. (1995) also investigated the presence of lattice defects and noted that electrodeposited nanocrystalline Ni and Niwt.%P had very few dislocations and thus, the dislocation density in these materials is considered to be very low. The presence of other lattice defects in these materials, for

–  –  –

example, stacking faults, still remains to be analyzed. Since the addition of Fe to Ni in the fcc phase is known to decrease the stacking fault energy [Charnock and Nutting (1967)], stacking faults are likely to be present. Although the presence of stacking faults has been reported in electrodeposited nanocrystalline Ni and Ni-Fe alloys [Yang et al. (2009), Wu et al.

(2006), Ebrahimi and Li (2003)], an in-depth analysis on both a qualitative and quantitative basis is still necessary. In general, additional information on grain boundary characteristics and lattice defects can lead to a better understanding of their possible effects on various material properties and behaviour.

The indentation behaviour of these electrodeposited nanocrystalline materials, e.g., hardness and Young’s modulus, has been studied in some detail. The hardness of nanocrystalline Ni was studied by El-Sherik et al. (1992) who observed a noticeable deviation from the regular Hall-Petch relationship. Nanocrystalline Ni-Fe alloys were also studied by Cheung et al. (1995) who showed a similar deviation from the regular Hall-Petch relationship but also noted that these changes were not due to any solid solution strengthening effect. Rather, the deviation from the Hall-Petch relationship is considered to be a result of a change in the dominant deformation mechanism [e.g., Chokshi et al. (1989)].

In the case of Young’s modulus, only electrodeposited nanocrystalline Ni-2.5wt.%P has been studied systematically with grain size [Zhou et al. (2003a), Zhou et al. (2003b)]. There remains the opportunity to also systematically study the Young’s modulus of electrodeposited nanocrystalline Ni and Ni-Fe alloys. In addition to the effect of grain size, alloying may also be taken into consideration along with other potentially influential factors such as anisotropy. Additionally, the potential effects of internal stresses on the properties of

–  –  –

these nanocrystalline materials should also be considered. For example, it has been suggested by Cammarata and Eby (1991) that the strains which result from decreasing grain size and the corresponding effect of interface stresses can produce higher order elastic effects.

That is, very fine grained materials may have slightly reduced Young’s moduli if internal stresses are present.

Electrodeposition processes typically produce materials that have some degree of internal stress [Schlesinger and Paunovic (2000)]. These internal stresses may be analyzed on both a microscopic and a macroscopic scale. For example, there are several studies which consider the effect of grain size on microstrain (or microstress) for electrodeposited Ni [Mishra et al. (2004), Wang (1997)] and Ni-Fe alloys [Li and Ebrahimi (2003)]. Generally speaking, microstrain results from atomic scale imperfections, e.g., dislocations, vacancies, grain boundaries, voids, inclusions [Macherauch and Kloos (1987)], which induce XRD line

–  –  –

nanocrystalline materials, various studies have shown that microstrain clearly increases with decreasing grain size, especially at less than 20 nm [e.g., Li and Ebrahimi (2003), Qin and Szpunar (2005)]. The nature of this microstrain has been related to observable local strains at grain boundaries using HR-TEM, e.g., for nanocrystalline Pd produced the inert gas condensation technique [Wunderlich et al. (1990)]. A systematic study over a broad grain size range to determine microstrain from XRD line broadening combined with an investigation on the grain boundary characteristics of electrodeposited nanocrystalline materials has yet to be carried out. In addition to this, an investigation on the presence of

–  –  –

lattice defects, such as stacking faults, may also reveal a contribution to microstrain induced XRD line broadening.

Macroscopic stresses (macrostresses) are manifested over large distances or many grains. These macrostresses cause shifting of the characteristic XRD lines [Macherauch and Kloos (1987)], or a detectable uniform strain [Cullity and Stock (2001)]. There are only a few studies which provide some insight into a microstructural relationship with macrostress.

For example, in an investigation on electrodeposited nanocrystalline Ni-Fe, Czerwinski (1996) established a relationship between grain size and macrostress in Fe-Ni alloy deposits (15wt.%Ni): a decrease in grain size is accompanied by a rise in macrostresses. The technique used in this study was the “bent-strip” method [Kouymdjiev (1985)] which is inexpensive and thus, quite popular in practice. However, this method has often produced results which are inconsistent from study to study. On the other hand, XRD methods are rarely used in practice, yet they offer the advantage of being substantially more accurate and consistent. El-Sherik et al. (2005) used an XRD method to measure the macrostress in electrodeposited nanocrystalline Ni (10 nm) and compared it with a large grain electrodeposited Ni (5000 nm) to find that the nanocrystalline electrodeposit had a macrostress which was about six times greater. A systematic study with grain size that covers a broad range using an XRD technique can provide a more accurate and consistent means to experimentally decipher a structure-macrostress relationship.





1.2. Research Objectives The research objectives of this study are based on the current opportunities for the

–  –  –

contribution of knowledge in this field. The synthesis technique employed in this study to produce the nanocrystalline Ni and Ni-Fe alloys was electrodeposition of foils in a continuous process. Using these materials, an intensive investigation into certain

characteristics and properties was carried out. The main research objectives were:

1. To synthesize a series of nanocrystalline Ni and Ni-Fe alloy foils spanning a broad grain size range using a novel continuous electrodeposition technique [Palumbo et al.

(2005)].

2. To characterize the series of nanocrystalline Ni and Ni-Fe alloys using X-ray diffraction (XRD), conventional and high-resolution transmission electron microscopy (HR-TEM), and thermal analysis. In particular, an attempt was made to divulge as much microstructural information as possible using HR-TEM for the purpose of assessing possible relationships with the behaviour of these materials.

3. To determine the hardness and Young’s modulus of these materials using the nanoindentation technique. In particular, Young’s modulus was studied extensively for any effect related to grain size and other possible influencing factors, such as alloying with Fe and anisotropy.

4. To determine the microstrain in these materials and evaluate the relationship with grain size. Additionally, to determine if there are other possible influencing factors, including lattice defects such as stacking faults which can arise from alloying with Fe.

–  –  –

5. To systematically determine the macrostresses from strain measurements using a twodimensional (2D) XRD technique as a function of grain size and investigate the origins of these macrostresses in electrodeposited nanocrystalline materials.

–  –  –

1.3. References Aus, M.J., Szpunar, B., A.M. El-Sherik, U. Erb, G. Palumbo and K.T. Aust, Scripta Metall.

Mater. 27 (1992) 1639.

Aus, M.J., “Magnetic Properties of Nanocrystalline Transition Metals”, Ph.D. Thesis, University of Toronto, 1999.

Bozorth, R., “Ferromagnetism”, Wiley-IEEE Press, New York, 1978.

Cammarata, R.C. and R.K. Eby, J. Mater. Res. 6 (1991) 888.

Charnock, W. and J. Nutting, Met. Sci. J. 1 (1967) 123.

Cheung, C.K.S., F. Djuanda, U. Erb and G. Palumbo, Nanostruct. Mat., 5 (1995) 513.

Chokshi, A.H., A.H. Rosen, J. Karch and H. Gleiter, Scripta Metall. Mater. 23 (1989) 1679.

Cullity, B.D. and S.R. Stock, “Elements of X-Ray Diffraction, Third Edition”, Prentice Hall, New Jersey, 2001.

Czerwinski, F., J. Electrochem. Soc. 143 (1996) 3327.

Ebrahimi, F. and H.Q. Li, Rev. Adv. Mater. Sci. 5 (2003) 134.

El-Sherik, A.M., U. Erb, G. Palumbo and K.T. Aust, Scripta Metall. Mater., 27 (1992) 1185.

El-Sherik, A.M., J. Shirokoff and U. Erb, J. All. Comp. 389 (2005) 140.

Erb, U., K.T. Aust and G. Palumbo, in “Nanostructured Materials: Processing, Properties, and Applications – 2nd Edition”, Ed. C.C. Koch, Noyes | William Andrew, New York, 2007.

Herzer, G., Scripta Metall. Mater. 33 (1995) 1741.

Kouymdiev, C.N., Surf. Technol. 26 (1985) 35, 45, 57.

Krstic, V.D., U. Erb and G. Palumbo, Scripta Metall. Mater. 29 (1993) 1501.

Li, H.Q. and F. Ebrahimi, Mater. Sci. Eng., A347 (2003) 93.

Macherauch, E. and K. H. Kloos, in: Residual Stresses in Science and Technology (E.

Macherauch and V. Hauk, ed.), Informationsgesellschaft, Oberursel, 1987.

Marsh, J.S., “The Alloys of Iron and Nickel: Volume I – Special Purpose Alloys”, McGrawHill Book Company, New York, 1938.

–  –  –

McCrea, J.L.M., G. Palumbo and U.Erb, in “Nanostructured Metals and Alloys: Processing, Microstructure, Mechanical Properties and Applications”, S.H. Whang, Woodhead Publishing, Philadelphia, 2011.

Mehta, S.C., D.A. Smith and U. Erb, Mat. Sci. Eng. A204 (1995) 227.

Mishra, R., B. Basu and R. Balasubramaniam, Mater. Sci. Eng. A 373 (2004) 370.

Nieman, G.W., J.R. Weertman and R.W. Siegel, J. Mater. Res. 6 (1991) 1012.

Palumbo, G., F. Gonzalez, K. Tomantschger, U. Erb and K.T. Aust, Plat. Surf. Finish. 90 (2003) 36.

Palumbo, G., I. Brooks, J. McCrea, G.D. Hibbard, F. Gonzalez, K. Tomantschger and U. Erb, United States Patent Application No. US 2005/0205425 A1, 2005.

Palumbo, G., S.J. Thorpe and K.T. Aust, Scripta Metall. Mater. 24 (1990) 1347.

Qin, W. and J.A. Szpunar, Phil. Mag. Lett. 85 (2005) 649.

Schlesinger, M. and M. Paunovic, “Modern Electroplating, Fourth Edition”, John Wiley & Sons, New York, 2000.

Van Petegem, S., F. Dalla Torre, D. Segers and H. Van Swygenhoven, Scripta Mater. 48 (2003) 17.

Wang, N., “Microstructures and Mechanical Properties of Nanocrystalline Materials”, Ph.D.

Thesis, University of Toronto, 1997.

Wang, N., Z. Wang, K.T. Aust and U. Erb, Mater. Sci. Eng. A237 (1997) 150.

Wu, X.-L., Y.T. Zhu and E. Ma, Appl. Phys. Lett. 88 (2006) 121905.

Wunderlich, W., Y. Ishida and R. Maurer, Scripta Metall. Mater. 24 (1990) 403.

Yang, F., W. Tian, C. Feng and B. Wang, Acta Metall. Sin. (Engl. Lett.) 22 (2009) 383.

Zhou, Y., U. Erb, K.T. Aust and G. Palumbo, Scripta Mater. 48 (2003) 825.

Zhou, Y., U. Erb, K.T. Aust and G. Palumbo, Z. Metallkd. 94 (2003) 1157.

Zhou, Y., S. Van Petegem, D. Segers, U. Erb, K.T. Aust and G. Palumbo, Mater. Sci. Eng.

A512 (2009) p.39.

Zugic, R., B. Szpunar, V.D. Krstic and U. Erb., Phil. Mag. A 75 (1997) 1041.

CHAPTER 2 Literature Review

2.1. Electrodeposited Nanocrystalline Metals and Alloys 2.1.1. Synthesis There have been many reports describing electrodeposits with ultra-fine structure [Safranek (1986), Schlesinger and Paunovic (2000)]. However, no systematic studies were published before the late 1980’s on the synthesis of nanocrystalline materials using the electrodeposition technique. This was the motivation for McMahon and Erb (1989) to carry out such investigations on electrodeposited nanocrystalline Ni-P alloys which eventually led to the identification of a process (Fig. 2.1) by Erb and El-Sherik (1994) and Erb et al. (1995) to electrodeposit a wide range of nanostructured metals and alloys with control over the grain size for the purpose of optimizing material properties.

Figure 2.1.

Electrochemical processing of nanocrystalline metals and alloys: (1) plating cell, (2) electrolyte, (3) anode, (4) ammeter, (5) power source, (6) cathode, (7) transistored switch, (8) wave generator, (9) oscilloscope, and (10) constant temperature bath [Erb et al. (1995)].

–  –  –

In this process, deposit growth conditions are controlled to favour massive nucleation regardless of coating thickness. These deposits show no cross-sectional structure transition from fine-grained-equiaxed to coarse-grained columnar structure with strong grain shape anisotropy, as in the case of conventional electrodeposits [Erb et al. (2007)]. In conventional electroplating, the deposit shows considerable gradients (through the thickness) in grain shape and size with most final grain sizes being larger than 1 μm (Fig. 2.2a). If the plating parameters are chosen such that massive crystal nucleation dominates over the crystal growth competition at any given stage in the plating process, a nanocrystalline structure over the entire thickness can be obtained (Fig. 2.2b).

–  –  –

2.1.2. Structure of Fully Dense Nanocrystals Gleiter (1989) first expressed the basic ideas surrounding the structure of nanomaterials where he recognized that large volume fractions of grain boundaries exist in materials with very small grain sizes. In particular, for grain sizes less than 20 nm, the grain

–  –  –



Pages:     | 1 | 2 || 4 | 5 |   ...   | 19 |


Similar works:

«FROM BAD TO WORSE: A SOCIAL CONTAGION MODEL OF ORGANIZATIONAL MISBEHAVIOR By Merideth J. Ferguson Dissertation Submitted to the Faculty of the Graduate School of Vanderbilt University in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY in Management May, 2007 Nashville, Tennessee Approved: Professor Bruce Barry Professor Ray Friedman Professor Neta Moye Professor Sandra Robinson ©Copyright 2007 by Merideth J. Ferguson All Rights Reserved ii To my boys, John and...»

«“STINKY AND SMELLY – BUT PROFITABLE”: THE CAPE GUANO TRADE, c.1843 – 1910 HENDRIK SNYDERS DISSERTATION PRESENTED FOR THE DEGREE OF DOCTOR OF PHILOSOPHY (HISTORY) IN THE FACULTY OF ARTS AND SOCIAL SCIENCES AT STELLENBOSCH UNIVERSITY PROMOTOR: PROFESSOR SANDRA S. SWART CO-PROMOTOR: PROFESSOR ALBERT. M. GRUNDLINGH DECEMBER 2011 1 University of Stellenbosch http://scholar.sun.ac.za DECLARATION By submitting this dissertation electronically, I declare that the entirety of the work contained...»

«Fruits and frugivory in neotropical primates and in Amazonian flooded and unflooded forests Joseph E. Hawes Thesis submitted for the degree of Doctor of Philosophy School of Environmental Sciences University of East Anglia, UK September 2012 © This copy of the thesis has been supplied on condition that anyone who consults it is understood to recognise that its copyright rests with the author and that no quotation from the thesis, nor any information derived therefrom, may be published without...»

«Entomotoxicological and Thermal Factors Affecting the Development of Forensically Important Flies Derek Reed Monthei Dissertation submitted to the Faculty of Virginia Polytechnic Institute and State University in partial fulfillment of the requirements for the degree of Doctor of Philosophy In Entomology Dr. Richard D. Fell, Chairperson Dr. Carlyle C. Brewster Dr. Sally Paulson Dr. Kevin Pelzer Dr. George S. Behonick Dr. Michelle R. Peace February 6th, 2009 Blacksburg, Virginia Tech Keywords:...»

«A HIDDEN LIGHT: JUDAISM, CONTEMPORARY ISRAELI FILM, AND THE CINEMATIC EXPERIENCE by Dan Chyutin BFA, Film Production, Tel Aviv University, 2005 MA, Cinema Studies, New York University, 2007 Submitted to the Graduate Faculty of The Kenneth P. Dietrich School of Arts and Sciences in partial fulfillment of the requirements for the degree of Doctor of Philosophy University of Pittsburgh 2015 UNIVERSITY OF PITTSBURGH DIETRICH SCHOOL OF ARTS AND SCIENCES This dissertation was presented by Dan Chyutin...»

«Confucianism as a Religious Tradition: Linguistic and Methodological Problems1 Joseph A. Adler Kenyon College Gambier, Ohio, USA Presented to the Institute for Advanced Studies in Humanities and Social Sciences, National Taiwan University (Taipei) and the Department of Philosophy, Tunghai University (Taichung) 2014 This paper is an attempt to sort out some of the semantic difficulties in judging whether or not the Confucian tradition can or should be considered a religion, a religious...»

«113 A Contribution to the Study of the Persian Concept of Âberu Magdalena Zaborowska* PL ISSN 0239–8818 HEMISPHERES Vol. 29, No. 1, 2014 A Contribution to the Study of the Persian Concept of Âberu Abstract The concept of âberu is one of those key concepts in Iranian culture which are very hard to define. In this paper the author attempts to explain its philosophical meaning, both by philological analysis based on dictionary sources and by placing it within the context of Iranian,...»

«  1   Curriculum Vitae for Chris Bobonich Personal Office: Philosophy Department Stanford University Stanford, CA 94305-2155 (650) 723-0807; sec'y 723-2547 email: bobonich@stanford.edu Home: 5 Pearce Mitchell Place Stanford University Stanford, CA 94305 (650) 326-9749 Education B.A. Harvard University, Government, June 1981 M. Phil. Cambridge University, Philosophy, June 1983 Ph.D. Berkeley, Philosophy, December 1990 Academic Positions 2010 on: Clarence Irving Lewis Professor of Philosophy...»

«“SEEING LIKE A ROVER”:IMAGES IN INTERACTION ON THE MARS EXPLORATION ROVER MISSION A Dissertation Presented to the Faculty of the Graduate School of Cornell University in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy by Janet Amelia Vertesi May 2009 © 2009 Janet Amelia Vertesi “SEEING LIKE A ROVER”:IMAGES IN INTERACTION ON THE MARS EXPLORATION ROVER MISSION Janet Amelia Vertesi, Ph.D. Cornell University 2009 This dissertation analyzes the use of images...»

«Kinetic Investigations of Thiolate Protected Gold Nanoparticles: Protein Interactions, Electron Transfer, and Precursor Formation By Brian N. Turner Dissertation Submitted to the Faculty of the Graduate School of Vanderbilt University in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Chemistry December, 2011 Nashville, Tennessee Approved: Professor David E. Cliffel Professor John A. McLean Professor James E. Crowe, Jr. Professor David W. Wright In Memory of...»

«MOURNING MEN IN EARLY ENGLISH DRAMA By ANDREW D. MCCARTHY A dissertation submitted in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY WASHINGTON STATE UNIVERSITY Department of English MAY 2010 © Copyright by ANDREW D. MCCARTHY, 2010 All Rights Reserved © Copyright by ANDREW D. MCCARTHY, 2010 All Rights Reserved ii ACKNOWLEDGMENTS First and foremost, I want to thank Will Hamlin, il miglior fabbro. From the moment I began thinking about lamenting men he has served...»

«YET ANOTHER ANTI-MOLINIST ARGUMENT∗ Dean Zimmerman Rutgers University I. Motivating Molinism Introduction “Molinism”, in contemporary usage, is the name for a theory about the workings of divine providence. Its defenders include some of the most prominent contemporary Protestant and Catholic philosophical theologians.1 Molinism is often said to be the only way to steer a middle course between two extremes: the radically opposed conceptions of foreknowledge, providence, and grace...»





 
<<  HOME   |    CONTACTS
2016 www.dissertation.xlibx.info - Dissertations, online materials

Materials of this site are available for review, all rights belong to their respective owners.
If you do not agree with the fact that your material is placed on this site, please, email us, we will within 1-2 business days delete him.