TITLE:
Phase-Transition Energies, New Characterization of Solid Materials and Anisotropy
AUTHORS:
Gerd Kaupp
KEYWORDS:
Instrumented Indentation, Loading Curve, Phase Transition Onset and Energy, Iteration-Less Plot, Physical Exponent, Present ISO Standard, Energy Law Violations, Physical Hardness, Error Detections
JOURNAL NAME:
Advances in Materials Physics and Chemistry,
Vol.9 No.4,
April
24,
2019
ABSTRACT: Non-iterative analysis of indentation results allows
for the detection of phase transitions under load and their transition energy.
The closed algebraic equations have been deduced on the basis of the physically
founded normal force depth3/2 relation. The precise transition onset position is obtained by linear
regression of the FN = kh3/2 plot, where k is the penetration resistance, which
also provides the axis cuts of both polymorphs of first order phase
transitions. The phase changes can be endothermic or exothermic. They are
normalized per μN or mN normal load. The analyses of indentation loading curves
with self-similar diamond indenters are used as validity check of the loading
curves, also from calibration standards that exhibit previously undetected
phase-transitions and are thus incorrect. The phase-transition energies for
fused quartz are determined from the loading curves from instrument provider
handbooks. The anisotropic behavior of phase transition energies is studied for
the first time. Quartz is a useful test object. The reasons for the
packing-dependent differences are discussed on the basis of the local crystal
structure under and around the inserting tip.