Zhang, H; de Luca, F; Wang, H; Mingard, K; Gee, M (2022) Deformation mechanism of WC single crystal under nanoindentation: effects of surface defects and orientation on pop-in and hysteresis. International Journal of Refractory Metals and Hard Materials, 106. 105850

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Abstract

Room temperature nanoindentation was carried out on tungsten carbide (WC) single crystals on the basal (0001) and prismatic (1010) planes, using both Berkovich and spherical indenters, in both single load and multi-load testing. Scanning electron microscopy and atomic force microscopy were used to characterise the deformed hardness impressions. The work focuses on correlating the load-displacement curves, including elastic to plastic deformation, size effect and hysteresis with the deformation behaviour of single crystals. It was found that with different specimen preparation processes the elastic to plastic deformation started at different threshold loads: This observation was found to be due to the variation in surface dislocation density. Staircase deformation was observed thought to be caused by dislocation motion and the formation of slip bands; sudden displacement discontinuities in the load-displacement response - associated with dislocation loop nucleation - occurred at, or near the theoretical shear strength. Furthermore, discontinuities in load-displacement curves were also used to confirm that hysteresis loops were a result of plastic deformation, as they when the loading was purely elastic.

Item Type:	Article
Keywords:	Nanoindentation, Surface defects, Pop-ins, Hysteresis, Strength
Subjects:	Advanced Materials > Mechanical Measurement
Divisions:	Materials and Mechanical Metrology
Identification number/DOI:	10.1016/j.ijrmhm.2022.105850
Last Modified:	18 Sep 2024 14:26
URI:	https://eprintspublications.npl.co.uk/id/eprint/10029