Abstract
Experimental results of microwedge indentation are presented in order to evaluate the thin film fine line on a thick substrate as a fracture mechanics test specimen. Crack length is found to be proportional to indentation volume, allowing assessment of adhesion. The amplitude of single-buckles is used to estimate induced residual stress in the fine line and adhesion is independently assessed. The phenomena of double-buckling and spallation during indentation are experimentally verified, and are used to estimate fracture toughness of the thin film columnar grain boundaries. Although values of adhesion are unreasonably high, cracking of the substrate occurred, violating the critical assumption of negligible substrate compliance. The amplitude assessment gives a more reasonable value. A hypothesis for the complete sequence of events is proposed.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 3177-3187 |
| Number of pages | 11 |
| Journal | Acta Materialia |
| Volume | 44 |
| Issue number | 8 |
| DOIs | |
| State | Published - Aug 1996 |
Bibliographical note
Funding Information:Acknonledgemenfs~This work was supported by ONR under grant No. NO00 14-89-J-l 726 for one of us (M. P. dB), and by DOE, Basic Sciences Div. under grant No. DE-FG07-84ER 45141 for W.W.G. and by a summer internship at Sandia National Laboratories, Livermore, CA. In particular, we would like to acknowledge the support of Dr Neville Moody at SNL in procuring the microwedge necessary for this work. Andrew Gardea at SNL provided help with data collection. M.P.dB acknowledges the University of Minnesota Graduate School for a doctoral dissertation fellowship. John Schwindeman, Brian Peters and Warren Oliver at Nano Instruments were very helpful in answering Nanoindenter questions. We also acknowledge Greg Haugstad for performing the RBS work at the University of Minnesota Center for Interfacial Engineering Ion Beam Analysis Facility. Discussions with Professor Rowland Cannon (UC Berkeley) and his research group were also helpful.