Competing Mechanisms between Dislocation and Phase Transformation in Plastic Deformation of Single Crystalline Yttria-Stabilized Tetragonal Zirconia Nanopillars

TL;DR

This study uses molecular dynamics simulations to explore how dislocation activity and phase transformation mechanisms influence the plastic deformation of single crystalline yttria-stabilized tetragonal zirconia nanopillars, revealing orientation-dependent behaviors.

Contribution

It is the first to reproduce tetragonal to monoclinic phase transformation in MD simulations for specific loading directions in YSTZ nanopillars.

Findings

Deformation mechanisms vary with crystallographic orientation.

Phase transformation can be experimentally reproduced in simulations.

Strength depends on the dominant deformation mechanism.

Abstract

Molecular dynamics (MD) is employed to investigate the plastic deformation mechanisms of single crystalline yttria-stabilized tetragonal zirconia (YSTZ) nanopillars under uniaxial compression. Simulation results show that the nanoscale plastic deformation of YSTZ is strongly dependent on the crystallographic orientation of zirconia nanopillars. For the first time, the experimental explored tetragonal to monoclinic phase transformation is reproduced by MD simulations in some particular loading directions. Three distinct mechanisms of dislocation, phase transformation, and a combination of dislocation and phase transformation are identified when applying compressive loading along different directions. The strength of zirconia nanopillars exhibits a sensitive behavior depending on the failure mechanisms, such that the dislocation-mediated deformation leads to the lowest strength, while the phase transformation-dominated deformation results in the highest strength.