Tensile behavior of tetragonal zirconia micro/nano‐fibers and beams in situ tested by push‐to‐pull devices

Abstract

The tensile mechanical behavior of tetragonal zirconia micro/nano‐fibers and beams was studied with push‐to‐pull (PTP) devices equipped in an in situ nanoindenter. The small‐volume ceramics generally experienced linear elastic deformation before fracture. Polycrystalline and oligocrystalline micro/nano‐fibers exhibit a tensile strength of ∼0.9–1.4 GPa, while single‐crystal beams exhibit a much higher tensile strength (∼2.1–3.2 GPa). The tensile strength of the small‐volume zirconia is found comparable to the corresponding compressive strength, which indicates the large discrepancy between the tensile and compressive strength observed in bulk zirconia becomes insignificant at micro/nano‐scales. No martensitic transformation induced shape memory strain was detected in the zirconia fibers and beams. Further variation in dopant concentration and crystal orientation was explored for single‐crystal beams and their significance in controlling the tensile strength was discussed. Our work offers a new insight into the mechanical behavior of tetragonal zirconia‐based ceramics at small scales.

Realizing reversible phase transformation of shape memory ceramics constrained in aluminum

“…In the past decade, the brittle nature of ZrO 2 has been mitigated by constructing miniature specimens (e.g., micro-/nano-pillars 8 , single/oligo-crystals 9 – 12 , nano-fibers 13 , 14 ), and structures formed thereof (e.g., honeycombs via 3D printing 15 , cellular foams via freeze casting 16 , 17 , and granular packings 3 , 18 ), where the ceramic is relatively free to expand/contract because of the high specific surface area and/or the removal of grain boundaries. Nevertheless, it remains a challenge to integrate these small-volume shape memory ceramics into a matrix material and realize their reversible phase transformation in a confined state without causing fracture.…”