A global investigation intoin situnanoindentation experiments on zirconia: from the sample geometry optimization to the stress nanolocalization using convergent beam electron diffraction

Abstract

A global investigation into in situ nanoindentation experiments on zirconia: from the sample geometry optimization to the stress nanolocalization using convergent beam electron diffraction E . C

Evidence for the formation of distorted nanodomains involved in the phase transformation of stabilized zirconia by coupling convergent beam electron diffraction and in situ TEM nanoindentation

“…The ion bombardment during the preparation could also have an impact on the results but we have shown in a previous work that ion implantation was mostly located on the top ten nanometers of the foil [16], while our observations were performed at its center.…”

“…If the stress stops, the regions can be resorbed; but if the stress persists or increases, they may remain, grow and therefore cause the transformation. A grain transformation is visible in conventional TEM imaging during nanoindentation [16]. However, the CBED mode is so localized that if too high a constraint is applied, the evolution of the pattern is no longer possible because the area is lost.…”

“…12Ce-TZP (CEZ-12 powder manufactured by Daiichi Company), whose tetragonal phase is stabilized with 12 mol. % of CeO2, was processed by uniaxial pressing at 200MPa and sintering at 1400 °C for 2 h. In a previous work, several sample preparation techniques for TEM examinations have been tested [16]. It appears that preparation by Focused Ion Beam (FIB) is the most suitable method for carrying coupled CBED and in situ nanoindentation experiments [17].…”

“…The thin foil of 12Ce-TZP was prepared by the "lift out" method [18] using a ZEISS Nvision 40 Focused Ion Beam microscope. At first a 400 nm-thick foil was made by milling (in order to avoid phase transformation [16]); then a final thinning was performed with weaker currents and voltages to obtain a final thickness of 120 nm (calculated by JEMS simulation [19] of CBED patterns in two beams condition on the sample).…”

“…The sample was cut with a wire saw and polished to a thickness of 30μm. Finally, an electron transparent window (150 nm thick, estimated by EELS [16]) was thinned using a FEI STRATA Dual Beam FIB.…”