Link to the University of Pittsburgh Homepage
Link to the University Library System Homepage Link to the Contact Us Form


Ennis, Brian Michael (2002) SUPER HARDENING OF W/NbN NANOLAYERS UNDER SHALLOW NANOINDENTATION. Master's Thesis, University of Pittsburgh. (Unpublished)

Primary Text

Download (3MB) | Preview


Superlattice materials are nanocomposites that exhibit a hardness at small bilayer repeat periods which exceeds the hardness predicted by the rule of mixtures for composites. The objective of this investigation was to utilize the experimental data obtained from nanoindentations and image scanning to examine the behavior of the superlattice material, W/NbN. Nanoindentations and in situ surface imaging were conducted over a range of applied loads on samples of W/NbN with two different bilayer periods (ƒ¼=5.6 nm and ƒ¼=10.4 nm), and monolithic samples of the niobium nitride (NbN) ceramic and the tungsten (W) metal which comprise the superlattice material. Additional shallow nanoindentations were made to a depth equal to the individual layer thicknesses of the nanocomposites. The mechanical properties were determined using the Oliver and Pharr method and compared for all the samples. The load versus displacement curves were also compared. The energies of indentation were calculated. The characteristics of the material pile-up resulting from the nanoindentations are determined from the scanned surface images. The experimental results are discussed to evaluate the influence of the different factors to the increase in hardness. The results indicate that the elastic modulus does not influence the hardness of the superlattice materials. The hardness and load versus displacement curves for the shallow indentations show little difference in behavior between NbN sample and the two superlattice materials. However, an increase in hardness is observed in the superlattice materials at deeper indentation depths. The results indicate that this increase in hardness is related to the nature of the interface between the layers in the superlattice materials.


Social Networking:
Share |


Item Type: University of Pittsburgh ETD
Status: Unpublished
CreatorsEmailPitt UsernameORCID
Ennis, Brian Michaelbmest1@pitt.eduBMEST1
ETD Committee:
TitleMemberEmail AddressPitt UsernameORCID
Committee ChairMao, Scott Xsmao@engr.pitt.eduSXM2
Committee MemberLovell, Michael Rmlovell@pitt.eduMLOVELL
Committee MemberSlaughter, William Swss@engr.pitt.eduWSS
Date: 2 December 2002
Date Type: Completion
Defense Date: 19 August 2002
Approval Date: 2 December 2002
Submission Date: 15 October 2002
Access Restriction: No restriction; Release the ETD for access worldwide immediately.
Institution: University of Pittsburgh
Schools and Programs: Swanson School of Engineering > Mechanical Engineering
Degree: MSME - Master of Science in Mechanical Engineering
Thesis Type: Master's Thesis
Refereed: Yes
Uncontrolled Keywords: multilayers; nanocomposites; nanoindentation
Other ID:, etd-10152002-092120
Date Deposited: 10 Nov 2011 20:03
Last Modified: 15 Nov 2016 13:50


Monthly Views for the past 3 years

Plum Analytics

Actions (login required)

View Item View Item