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



Pages:     | 1 |   ...   | 12 | 13 || 15 | 16 |   ...   | 19 |

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

-- [ Page 14 ] --

Hume-Rothery, W. and G.V. Raynor, “The Structure of Metals and Alloys, Monograph 1, Institute of Metals, London, 1983.

Jartych, E., M. Budzynski and J.K. Zurawicz, Hyperfine Interact. 73 (1992) 255.

Jette, E. and F. Foote, Trans. Am. Inst. Min. Met. Eng. 120 (1936) 259.

Klement, U., U. Erb, A.M. El-Sherik and K.T. Aust, Mater. Sci. Eng. A203 (1995) 177.

Klement, U., U. Erb and K.T. Aust, Nanostruct. Mater. 6 (1995) 581.

Klug, H.P. and L.E. Alexander, “X-ray Diffraction Procedures”, John Wiley & Sons, New York, 1974.

Krill, C.E. and R. Birringer, Phil. Mag. A77 (1998) 621.

Leith, S.D., S. Ramli and D.T. Schwartz, J. Electrochem. Soc. 146 (1999) 1431.

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

Li, D.X., D.H. Ping, J.Y. Huang, Y.D. Yu and H.Q. Ye, Micron 31 (2000) 581.

Lu, K., R. Luck and B. Predel, Scripta Metall. Mater. 28 (1993) 64.

McMahon, G. and U. Erb, J. Mater. Sci. Lett., 8 (1989) 865.

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

Murr, L.E., “Interfacial Phenomena in Metals and Alloys”, Addison-Wesley, London, 1975.

Nakahara, S., J. Cryst. Growth. 55 (1981) 281.

Nie, X., R. Wang, Y. Ye, Y. Zhou and D. Wang, Solid State Commun. 96 (1995) 729.

Osmond, F. and G. Cartaud, “Sur Les Fers Meteoriques”, Revue De Metallurgie (1904) 70.

Owen, E.A., E.L. Yates and A.H. Sully, Proc. Phys. Soc. 49 (1937) 315.

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

–  –  –

Ping, D.H., D.X. Li and H.Q. Ye, J. Mater. Sci. Lett. 14 (1995) 1536.

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

Reed-Hill, R.E. and R. Abbaschian R, “Physical Metallurgy Principles, 3rd Edition”, PWS Publishing Company, Boston, 1994.

Sambongi, T., J. Phys. Soc. Jap. 20 (1965) 1370.

Scott, W.W., Jr., Alloy Phase Diagrams, Vol. 3 (ASM Handbook), ASM International, Materials Park, OH, 1992.

Soong, C., “Thermal Stability of Nanocrystalline Nickel Electrodeposited from an AdditiveFree Electrolyte”, M.A.Sc. Thesis, University of Toronto, 2009.

Thornton, P.R., T.E. Mitchell and P.B. Hirsch, Phil. Mag. 7 (1962) 1348.

Tiwari, G.P. and R.V. Ramanujan, J. Mater. Sci. 36 (2001) 271.

Turi, T., “Thermal and Thermodynamic Properties of Fully Dense Nanocrystalline Ni and Ni-Fe Alloys”, Ph.D. Thesis, University of Toronto, 1997.

Valiev, R.Z., R.K. Islamagaliev and I.V. Alexandrov, Prog. Mater. Sci. 45 (2000) 103.

Valiev, R.Z., V.Yu. Gertsman and O.A. Kaibyshev, Phys. Stat. Sol. A 97 (1986) 11.

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

Wang, N., Z. Wang, K.T. Aust and U. Erb, Acta Mater. 45 (1997) 1655.

Wang, Z., Phil. Mag. 84 (2004) 351.

Wei, H.-H., “Tensile Properties of Nanocrystalline Ni-Fe Alloys”, M.A.Sc. Thesis, University of Toronto, 2006.

Williams, D.B. and C.B. Carter, “Transmission Electron Microscopy, 2nd Edition”, Springer Science, New York, 2009.

Willson, K.S. and J.A. Rogers, Tech. Proc. Am. Electroplaters Soc. 51 (1964) 92.

Wu, X., E. Ma and Y.T. Zhu, J. Mater. Sci. 42 (2007) 1427.

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

A512 (2009) 39.

CHAPTER 5 Indentation Behaviour*

5.1. Introduction One of the objectives of this study was to examine two important properties, namely the hardness and Young’s modulus of nanocrystalline Ni with varying grain sizes and nanocrystalline Ni-Fe alloys as a function of Fe concentration and/or grain size. The study will also consider the effects of other important factors that are known to influence Young’s modulus, especially preferred crystallographic orientation, or texture. A better understanding of the effect of grain size on the Young’s modulus of nanocrystalline Ni-Fe alloys is of particular interest because of the unusual effect of composition observed for these alloys in the polycrystalline form. In contrast to polycrystalline Ni-Cu alloys, which show a relatively linear decrease in Young’s modulus with increasing Cu concentration [Guy (1972)], polycrystalline Ni-Fe alloys show a deep minimum at about 60wt.% Fe (as shown in Fig. 5.1) even though pure Fe and pure Ni have almost the same Young’s modulus values [Ledbetter and Reed (1973)].

It should also be pointed out that although a general trend in Fig. 5.1 is obvious, for any given composition including the pure materials, there are significant variations in the data presented in different studies. The Young’s modulus trend for the Ni-Fe alloys may be explained based on the fact that at greater than 60wt.%Fe, there is a transition from the fcc phase to the bcc phase. On the other hand, the Ni-Cu alloys do not show this behaviour because it remains in the fcc phase over the entire compositional range.

*

The key findings presented in this chapter were previously published in the following refereed journal article:





J.D. Giallonardo, U. Erb, K.T. Aust and G. Palumbo, “The influence of grain size and texture on the Young’s modulus of nanocrystalline nickel and nickel-iron alloys”, Philosophical Magazine, 91 (2011) 4594.

–  –  –

5.2. Results The hardness and Young’s modulus for each sample were determined using nanoindentation as described in Chapter 3 (Section 3.6). The last elastic unloading curves were analyzed to determine the Young’s modulus using the procedure outlined by Oliver and Pharr (1992). An example of a series of load-unload curves in a force-depth graph is shown

–  –  –

in Fig. 5.2 for five different loads (150, 130, 110, 90 and 70 mN) performed at a loading rate of 13.3 mN/s. Table 5.1 summarizes the hardness and Young’s modulus results for each of the samples. The errors reported in the table and figures correspond to one standard deviation. For discussion purposes, the orientation indices that were determined in Chapter 4 (Table 4.5) are also provided in Table 5.1. As expected, the hardness values gradually increase with decreasing grain size. The measured Young’s modulus values, Em, have some noticeable differences when compared to the literature values, E0, for polycrystalline materials. These observations are discussed in the subsequent sections.

5.3. Effect of Grain Size on Hardness A plot of the hardness values with the inverse square root of the average grain size for all materials produced (Fig. 5.3) shows a transition from regular to inverse Hall-Petch behaviour which is in agreement with previous studies [El-Sherik et al. (1992), Erb et al.

(1996), Cheung et al. (1995), Ebrahimi et al. (1999), and Li and Ebrahimi (2003)]. The slope for the region representing regular Hall-Petch behaviour was determined to be approximately 24 GPa/nm-1/2 which is similar to 28 GPa/nm-1/2 reported by Hughes et al. (1986) for electrodeposited nanocrystalline Ni with grain sizes in the range of 12 to 12,500 nm. It should be noted that solid solution hardening in the Ni-Fe alloys was previously found to be insignificant compared to grain size hardening [Erb et al. (1996), Cheung et al. (1995)].

Several interpretations have been given to explain deviations from the regular HallPetch behaviour. When the grain size is sufficiently small, i.e., less than 20 nm, dislocation slip is no longer the dominant deformation mechanism. As a result, deviations from the Hall

–  –  –

Figure 5.3.

Hall-Petch plot for the series of nanocrystalline Ni and Ni-Fe alloys.

Petch relationship are observed and other deformation mechanisms begin to operate.

Chokshi et al. (1989) observed a similar behaviour for nanocrystalline Cu and Pd produced using the inert gas condensation technique and suggested that room temperature Coble (Nabarro-Herring) creep occurs and is possible at this temperature because of the relatively

–  –  –

nanocrystalline Ni-P alloys, Palumbo et al. (1990b) owed deviations from regular Hall-Petch behaviour to the fact that triple lines account for a significant fraction of the bulk volume, especially when the grain size is less than 20 nm. The deformation of electrodeposited nanocrystalline Ni over a broad grain size range of 40 to 6 nm was analyzed by Wang et al.

(1997). They demonstrated that at high stress levels, grain boundary sliding is essentially the main room temperature deformation mechanism, although creep mechanisms can contribute

–  –  –

significantly at small grain sizes. Wang et al. (1997) proposed that the deviations from the Hall-Petch relationship are caused by a dynamic creep process due to diffusion mechanisms.

5.4. Effect of Grain Size on Young’s Modulus Table 5.1 summarizes the Young’s modulus measurement data for each of the samples. Depending on the load and sample, indentation depths ranged between approximately 0.8 and 1.5 µm, i.e., ≤ 3% of the sample thickness. The Young’s modulus for the Ni samples was measured and the values obtained were found to be similar to conventional (randomly oriented) polycrystalline Ni, ~207 GPa [Davis (1990)], down to an average grain size of about 20 nm. The Young’s modulus for the nanocrystalline Ni-Fe alloys was also measured; however, for comparative purposes, values for conventional (randomly oriented) polycrystalline Ni-Fe counterparts with the exact same compositions were not available. Instead, a comprehensive collection of data for the complete range of conventional (randomly oriented) polycrystalline Ni-Fe alloys was compiled earlier by Ledbetter and Reed (1973), shown in Fig. 5.1. For the fcc phase polycrystalline Ni-Fe alloys, there is a notable variation and distinct trend with increasing Fe concentration. From about 0 to 20 wt.%Fe, the Young’s modulus is relatively constant. This is then followed by a decrease down to a minimum average value of ~140 GPa at around 60wt.%Fe. Increasing the Fe concentration in the nanocrystalline Ni-Fe alloys shows a similar trend (Table 5.1). In order to compare the values obtained for nanocrystalline Ni-Fe alloys to their conventional (randomly oriented) polycrystalline counterparts, an average of the Young’s modulus values, was taken from the collection of data [Ledbetter and Reed (1973)] for compositions close to the four alloys obtained in the current study. The measured values were then normalized,

–  –  –

Em / E0, where Em is the measured value and E0 is the respective conventional (randomly oriented) polycrystalline counterpart value, and then plotted as a function of grain size (Fig.

5.4). In the case of Ni, E0 is the value of its conventional polycrystalline counterpart value, ~207 GPa [Davis (1990)].

1.2 1.1

–  –  –

Figure 5.4.

Normalized Young’s modulus values as a function of grain size. The horizontal solid line represents Em / E0 = 1, where Em is the measured value and E0 is the respective conventional (randomly oriented) polycrystalline counterpart value. The dashed lines correspond to the values predicted by the upper bound composite model (Eq. 5-1). The solid lines correspond to the values predicted by the lower bound (Eq. 5-2) composite model.

The effect of decreasing grain size on Young’s modulus was previously investigated by Shen et al. (1995) for nanocrystalline Fe produced by mechanical attrition. Zhou et al.

(2003a), Zhou et al. (2003b), and Zhou et al. (2009) also investigated the effect of grain size on the Young’s modulus of electrodeposited Ni-2.5wt.%P. In both cases, the influence of the various structural components (grain interiors, grain boundaries, and triple junctions) in nanocrystalline materials [Palumbo et al. (1990a)] was estimated according to a simple rule

–  –  –

of mixtures by considering their volume fractions in a composite model and taking into consideration both upper (Eq. 5-1) and lower (Eq. 5-2) bound solutions [Callister (2005)],

–  –  –

where, Em is the measured Young’s modulus of the material, f g ( E g ), f gb ( E gb ) and f tj ( Etj ) the volume fractions (average Young’s moduli) for grain interiors, grain boundaries and triple junctions, respectively. Note that the upper bound solution (Eq. 5-1) is based on the isostrain condition while the lower bound is based on the isostress condition. Volume fractions were calculated by using a reasonable range for grain boundary thicknesses of 0.7 and 1.1 nm [Kirchheim et al. (1988)] and assuming a three-dimensional tetrakaidecahedral model for the crystal shape [Palumbo et al. (1990a)] using Eq. 2-1, 2-2, 2-3, and,

–  –  –

where, f ic is the total intercrystal volume fraction. The value for E g is considered to be the same as that of the conventional (randomly oriented) polycrystalline counterparts. The values for E gb and Etj are taken to be about 76% and 73%, respectively, of the value for the conventional polycrystalline counterparts [Zhou et al. (2003b)]. Normalized values, for Young’s modulus were then plotted in Fig. 5.4 as a function of grain size along with the composite model predictions for the upper bound (dashed lines) and lower bound (solid lines) solutions using both grain boundary thicknesses.

–  –  –



Pages:     | 1 |   ...   | 12 | 13 || 15 | 16 |   ...   | 19 |


Similar works:

«A Commentar y on the Upanishads by Swami Nirmalananda Giri 1 © Atma Jyoti Ashram http://www.atmajyoti.org http://blog.atmajyoti.org 2 A Commentar y on the Isha Upanishad Seeing All Things in God Introduction to the Upanishads The sacred scriptures of India are vast. Their importance is ranked differently according to the particular viewpoint of the individual. In Hinduism there are six darshanas, or systems of philosophy. They often seem to contradict themselves (and their professed adherents...»

«Zinc Oxide Transparent Thin Films For Optoelectronics by Karthik Sivaramakrishnan A Dissertation Presented in Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy Approved November 2011 by the Graduate Supervisory Committee: Terry L Alford, Chair Dieter K Schroder Nathan Newman David Theodore ARIZONA STATE UNIVERSITY December 2010 ABSTRACT The object of this body of work is to study the properties and suitability of zinc oxide thin films with a view to engineering them...»

«Progressive Partial Memory Learning A Dissertation Submitted to the Graduate Faculty of George Mason University in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy, Information Technology By Marcus A. Maloof Bachelor of Science University of Georgia, 1989 Master of Science University of Georgia, 1992 Director: Ryszard S. Michalski, PRC Chaired Professor Departments of Computer Science and Systems Engineering Fall 1996 George Mason University Fairfax, Virginia ii...»

«The Council of Yahweh: Its Structure and Membership by Marylyn Ellen White A Thesis submitted to the Faculty of Theology of the University of St. Michael’s College in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Theology Awarded by the University of St. Michael’s College © Copyright by Marylyn Ellen White 2012   ii   The Council of Yahweh: Its Structure and Membership Marylyn Ellen White Doctor of Philosophy in Theology University of St. Michael’s...»

«ABSTRACT Title of Dissertation: ABLE-BODIED WOMANHOOD: DISABILITY TROPES AND CORPOREALLY EXCLUSIONARY NARRATIVES IN THE RHETORIC OF BLACK AND WHITE WOMEN’S RIGHTS DISCOURSES, 1832-1932 Heidi A Temple, Doctor of Philosophy, 2016 Dissertation directed by: Dr. Nancy L. Struna, Chair and Professor, American Studies Department This project is a feminist disability rhetorical analysis of US black and white women’s rights movements from 1832-1932. Guided by Disability and Feminist Theory, it works...»

«Uncertainty, Reward, and Attention in the Bayesian Brain. Louise Whiteley Dissertation submitted for the degree of doctor of philosophy of the university of london Gatsby computational neuroscience unit university college london 1 Declaration I, Louise Emma Whiteley, confirm that the work presented in this thesis is my own. Where information has been derived from other sources, I confirm that this has been indicated in the thesis. 17th September 2008 2 Abstract The ‘Bayesian Coding...»

«Quantum Solids of Two Dimensional Electrons in Magnetic Fields Yong P. Chen A Dissertation Presented to the Faculty of Princeton University in Candidacy for the Degree of Doctor of Philosophy Recommended for Acceptance by the Department of Electrical Engineering November 2005 c Copyright by Yong P. Chen, 2006. All Rights Reserved I certify that I have read this thesis and that in my opinion it is fully adequate, in scope and in quality, as a dissertation for the degree of Doctor of Philosophy....»

«Young Children’s Representations of Emotions and Attachment in Their Spontaneous Patterns of Behaviour: An Exploration of a Researcher’s Understanding C. Arnold PhD Young Children’s Representations of Emotions and Attachment in Their Spontaneous Patterns of Behaviour: An Exploration of a Researcher’s Understanding C. Arnold PhD “A thesis submitted in partial fulfilment of the University’s requirements for the degree of Doctor of Philosophy” Awarding Institution: Coventry...»

«Command Hallucinations and the Risk of Violence and Self-Harm: What distinguishes compliers from non-compliers? Elizabeth Andrew Thesis submitted for the degree of Doctor of Philosophy Cardiff University 2010 UMI Number: U584482 All rights reserved INFORMATION TO ALL USERS The quality of this reproduction is dependent upon the quality of the copy submitted. In the unlikely event that the author did not send a complete manuscript and there are missing pages, these will be noted. Also, if...»

«Department of Educational Administration Doctoral Degree K-12 Educational Administration Student / Faculty Handbook For accepted / enrolled students Last Updated: 08/20/2015 TABLE OF CONTENTS I. Program Overview • PhD Program Mission and Philosophy • PhD Program Expectations II. Program Components Credit Accrual Preliminary • Exam Comprehensive • Exam Research Practicum • Dissertation Proposal • Dissertation Defense • III. Degree Requirements Residency Requirement • Time...»

«PHASE TRANSITIONS AND ANOMALOUS COMPRESSIBILITY IN 1-2-2 Fe-BASED SUPERCONDUCTORS by WALTER O. UHOYA YOGESH K. VOHRA, COMMITTEE CHAIR LOWELL E. WENGER DAVID J. HILTON ATHENA S. SEFAT KEVIN M. HOPE A DISSERTATION Submitted to the graduate faculty of The University of Alabama at Birmingham, in partial fulfillment of the requirements for the degree of Doctor of Philosophy BIRMINGHAM, ALABAMA 2014 Copyright by Walter O. Uhoya 2014 PHASE TRANSITIONS AND ANOMALOUS COMPRESSIBILITY IN 1-2-2 FeBASED...»

«Analyzing Challenges and Opportunities of the Implementation of e-Government Initiatives for Development through the Lens of the Capability Approach: Case Studies from Mozambique By: Gertrudes Adolfo Macueve Submitted as partial fulfilment of the requirements for the degree of Doctor of Philosophy (Ph. D) Faculty of Mathematics and Natural Sciences Department of Informatics University of Oslo Norway August 14, 2008 Dedication To my parents, Deolinda Noé and Adolfo A. Macueve TABLE OF CONTENTS...»





 
<<  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.