Abstract
A conventional microhardness tester has been instrumented with a piezoelectric load cell and capacitance displacement gages to measure load and displacement during indentation. As in other recently-developed load and displacing sensing indentation instruments, the new device can be used to measure a variety of mechanical properties, but has the advantage of being relatively inexpensive to assemble since many of its components are standard equipment. Tests were performed on soda-lime glass and an aluminum alloy, demonstrating the diversity of material elastic-plastic responses under indentation, particularly in the unloading cycle. The data suggest that models of elastic unloading based on invariant indenter-surface contact area may not be general, and may lead to underestimates of hardness and modulus.
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Pharr, G.M., Cook, R.F. Instrumentation of a conventional hardness tester for load-displacement measurement during indentation. Journal of Materials Research 5, 847–851 (1990). https://doi.org/10.1557/JMR.1990.0847
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DOI: https://doi.org/10.1557/JMR.1990.0847