Please consider attending the following: MATERIALS ENGINEERING SEMINAR "Mechanical Behavior of Yttria Stabilized Zirconia at Microscale" By Jaehun Cho Purdue MSE Ph.D. Preliminary Exam Advisor: Professor Xinghang Zhang ABSTRACT Yttria stabilized zirconia (YSZ) has metastable tetragonal phase at room temperature, which can transform into monoclinic phase with ~ 4% volume expansion under an applied external stress. The phase transformation (martensitic transformation) occurs near a crack tip where the external stress is concentrated and hinders a crack propagation by generating a compressive strain field, thereby enhancing toughness and strength. Recently, it is known that miniaturization of a specimen increases toughness of YSZ by decreasing mismatch stress among grains during martensitic transformation. Furthermore, it turns out that superelasticity and shape memory effect can be tremendously enhanced by scaling down the specimen. In this study, the concept of martensitic transformation and the factors affecting its effectiveness will be explored. Also, the mechanical properties of YSZ at macroscale and microscale will be compared. Lastly, the enhanced superelasticity and shape memory effect will be reported. Date: Thursday, September 28, 2017 Time: 1:30 P.M. Place: ARMS 1028