Factors limiting the accuracy of mechanical-property measurement by nanoindentation

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dc.contributor.advisorPharr, George M.en_US
dc.creatorTsui, Ting Yiuen_US
dc.date.accessioned2009-06-04T08:42:04Zen_US
dc.date.available2009-06-04T08:42:04Zen_US
dc.date.issued1997en_US
dc.description.abstractNanoindentation techniques have been widely used to measure thin film mechanical properties. One of the most commonly used methods of analysis of nanoindentation load and displacement data was developed by Oliver and Pharr. The objective of this dissertation is to examine some of the limitations of this method and develop improvements so that a more accurate hardness and elastic modulus measurements can be made. Detailed experimental studies of bulk monolithic materials and soft films on hard substrates were performed to evaluate the validity of the Oliver and Pharr experimental technique and analysis procedures. Three different indenters were used. They were the Berkovich and Vickers pyramids, and a cone with a 70.3$\sp\circ$ included angle. It is shown that there are inherent limitations in the Oliver and Pharr indenter shape-function calibration method which means that it cannot be applied to the blunt Vickers and conical indenters used in this work. A new procedure was developed which avoids these problems. The pile-up behavior of monolithic and thin film materials was extensively investigated. Experimental results for monolithic materials show that materials with low elastic modulus to hardness ratios (E/H) such as ceramics are less likely to pile-up. On the other hand, monolithic materials which have high E/H ratios and low strain hardening coefficients or soft films on hard substrates are more likely to pile-up. The pile-up generated during the indentation process in these materials can create as much as 50% more contact area between the indenter and the specimen. The effects of pile-up on the hardness and elastic modulus measurements for monolithic and thin film materials were examined. It is shown that when pile-up occurs, Oliver and Pharr method overestimates both the hardness and the elastic modulus. Only if these extra contact area generated by the pile-up is included are the correct hardness and elastic modulus values obtained. The amount of pile-up is also found to depend on the indenter geometry. The Vickers indenter generates more pile-up at the indentation corners than the Berkovich indenter for both monolithic materials and soft films on hard substrates. The absolute amount of pile-up in monolithic materials for Vickers indentations is also more than the Berkovich.en_US
dc.format.extent332 p.en_US
dc.format.mimetypeapplication/pdfen_US
dc.identifier.callnoTHESIS M.E. 1997 TSUIen_US
dc.identifier.citationTsui, Ting Yiu. "Factors limiting the accuracy of mechanical-property measurement by nanoindentation." (1997) Diss., Rice University. <a href="https://hdl.handle.net/1911/19223">https://hdl.handle.net/1911/19223</a>.en_US
dc.identifier.urihttps://hdl.handle.net/1911/19223en_US
dc.language.isoengen_US
dc.rightsCopyright is held by the author, unless otherwise indicated. Permission to reuse, publish, or reproduce the work beyond the bounds of fair use or other exemptions to copyright law must be obtained from the copyright holder.en_US
dc.subjectEngineeringen_US
dc.subjectMaterials scienceen_US
dc.titleFactors limiting the accuracy of mechanical-property measurement by nanoindentationen_US
dc.typeThesisen_US
dc.type.materialTexten_US
thesis.degree.departmentMechanical Engineeringen_US
thesis.degree.disciplineEngineeringen_US
thesis.degree.grantorRice Universityen_US
thesis.degree.levelDoctoralen_US
thesis.degree.nameDoctor of Philosophyen_US
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