High frequency acoustic emission monitoring in nano-impact of alumina and partially stabilised zirconia

• Published in: Materials science & engineering. A, Structural materials : properties, microstructure and processing Structural materials : properties, microstructure and processing, 2020-04, Vol.780, p.139159, Article 139159
• Main Authors: Beake, Ben D., Ctvrtlik, Radim, Harris, Adrian J., Martin, Alberto Sanchez, Vaclavek, Lukas, Manak, Jan, Ranc, Vaclav
• Format: Article
• Language: English
• Subjects: Acoustic emission; Aluminum oxide; Ceramics; Cracking (fracturing); Diamond pyramid hardness; Electron microscopy; Fracture mechanics/fracture behavior/fatigue; High frequencies; High strain rate; Impact tests; Indenters; Ion beams; Micromechanics; Monitoring; Partial stabilization; Partially stabilized zirconia; Penetration depth; Zirconium dioxide
• ISSN: 0921-5093; 1873-4936
• DOI: 10.1016/j.msea.2020.139159

High frequency acoustic emission monitoring is proving a useful technique in improving the understanding of deformation processes occurring in nano- and micro-scale mechanical contacts. In this study AE monitoring has been used to investigate the fracture of alumina and MgO-partially stabilised zirconia (PSZ) at high strain rate in repetitive nano-impact tests with cube-corner and 5 μm radius spherical diamond indenters. Focussed ion beam milling of impact craters revealed sub-surface intergranular cracking on alumina and sub-surface transgranular cracking on PSZ. The evolution of AE through the test was strongly dependent on the geometry of the indenter used to create the impacts. AE energy was generally much higher when impacts cause rapid increases in penetration depth, with single high energy hits observed on abrupt depth bursts in tests with the cube corner indenter. The damage progression in tests with the spherical indenter differed between the ceramics, with more AE events near the start of the test on alumina and later in the test for PSZ. Reasons for these differences are discussed. •Novel integration of acoustic emission monitoring and nano-impact testing.•Sub-surface cracking in ceramics revealed by focussed ion beam milling.•Acoustic emission record explains differences in damage evolution processes.