Evidence of Stress Development as a Source of Driving Force for Grain-Boundary Migration in a Ni Bicrystalline TEM Specimen

• Main Authors: Sung Bo Lee, Jinwook Jung, Heung Nam Han
• Format: Article
• Language: English
• Published: MDPI AG 2020-01-01
• Series: Materials
• Subjects: nickel; transmission electron microscopy (tem); grain-boundary migration; stress development; stacking fault
• Online Access: https://www.mdpi.com/1996-1944/13/2/360

In a previous study, using high-resolution transmission electron microscopy (HRTEM), we examined grain-boundary migration behavior in a Ni bicrystal. A specimen for transmission electron microscopy (TEM) was prepared using focused ion beam. The Ni lamella in the specimen was composed of two grains with surface normal directions of [1 0 0] and [1 1 0]. As the lamella was heated to 600 °C in a TEM, it was subjected to compressive stresses. The stress state of the Ni lamella approximated to the isostress condition, which was confirmed by a finite element method. However, the stress development was not experimentally confirmed in the previous study. In the present study, we present an observation of stacking faults with a length of 40−70 nm at the grain boundary as direct evidence of the stress development.