Influence of modulus-to-hardness ratio and harmonic parameters on continuous stiffness measurement during nanoindentation. (1st August 2017)

• Record Type: Journal Article
• Authors: Merle, Benoit; Maier-Kiener, Verena; Pharr, George M.
• Is Part Of: Acta materialia. Volume 134(2017)
• Page Start: 167
• Page End: 176
• Publication Date: 2017-08-01
• Subjects: Nanoindentation -- Continuous stiffness measurement -- Harmonic parameters -- Lock-in amplifier -- Stiffness bias; Materials -- Periodicals; Materials science -- Periodicals; Materials -- Mechanical properties -- Periodicals; Metallurgy -- Periodicals; Chemistry, Inorganic -- Periodicals; 620.112
• DOI: 10.1016/j.actamat.2017.05.036
• Languages: English
• ISSNs: 1359-6454

Abstract

Abstract: Dynamic nanoindentation is a popular method for continuously probing the mechanical properties of a sample as a function of depth. It is shown here that special caution should be exercised when testing materials with high modulus-to-hardness ratios (E/H) at fast loading rates, as the choice of harmonic parameters can result in a significant underestimation of the contact stiffness and hence the elastic modulus. The origin of this behavior is traced back to a bias occurring during signal processing by the lock-in amplifier. The possible consequences of flawed measurements are highlighted and a practical method for detecting possible occurrence from the phase angle signal is presented. Graphical abstract: