Grain Boundaries, Interfaces, and Surfaces in Functional Materials: Fundamental Structure-Property-Performance Relationships: Poster Session
Sponsored by: ACerS Basic Science Division
Program Organizers: Catherine Bishop, University of Canterbury; John Blendell, Purdue University; Shen Dillon, University of Illinois at Urbana-Champaign; Wolfgang Rheinheimer, Purdue University; Ming Tang, Rice University; Melissa Santala, Oregon State University
Tuesday 10:00 AM
November 3, 2020
Room: Poster Hall
Location: MS&T Virtual
The Impact of Metastable Grain Boundary States on Mobility in FCC Metal: Yutong Bi1; Ian Chesser1; Elizabeth Holm1; 1Carnegie Mellon University
In this work, we study the influence of metastable states on grain boundary mobility with atomistic simulations. We apply synthetic driving force to three different ∑5(210) grain boundary structures (Normal Kites, Filled Kites, Split Kites) at a variety of temperatures and driving force magnitudes. The maximum density SK structure was found to have the highest mobility at low driving forces and lowest mobility at high driving forces. Meanwhile, a change in shear coupling mode and vacancy ejection was observed for SK at high driving forces. This change in grain boundary migration indicates a potential grain boundary phase transition. Moving boundaries were quenched to 0K framewise to calculate excess properties in order to determine the presence of a grain boundary phase transition.
Thermal Property of Diamond Thin Film on Si (100) Substrate: Chunyan Zhang1; Joseph P. Feser1; Chaoying Ni1; 1University of Delaware
The thermal conductivity (κ) of a thin film is important in electronic devices because the capability to transport heat is often a factor to limit the device performance. In this work, we investigated the thermal property of polycrystalline diamond film deposited on single crystal Si (100) substrate. The interfacial microstructure was characterized by TEM and the interfacial thermal resistance (G) and κ were measured by time-domain thermoreflectance method. The diamond thin film was found to have a κ value of 240.93 W/(mK) which is greatly smaller than that of bulk diamond (up to 2200 W/(mK)) and a G value of 0.018 GW/(m2K). The amorphous transition layer captured by TEM, large Debye temperature and lattice constant mismatch between diamond and Si cause an increase in the interfacial thermal resistance. The low κ is due to grain boundary scattering and a thinner film thickness shorter than the MFP of phonon in diamond.
Vacancy-enhanced Grain Boundary Migration: Shuozhi Xu1; Dengke Chen2; Yashashree Kulkarni3; 1University of California, Santa Barbara; 2Georgia Institute of Technology; 3University of Houston
Grain boundaries (GBs) are key players in the plasticity, damage, and failure of polycrystalline materials. A quantitative description of GB-mediated processes, such as migration, sliding, and defect interactions, is hence vital for optimizing the properties of the polycrystal through mechanical processing and has been the subject of long-standing interest. Conventional understanding is that point defects, including vacancies, interstitials, and substitutional atoms, have a drag effect, thereby hindering GB migration. In this work, using atomistic simulations, we reveal that vacancies serve as energetically favorable sites for the nucleation of GB disconnections, thereby inducing shear-coupled migration of certain GBs. Fully 3D nudged elastic band-based calculations demonstrate that vacancies weaken the line tension of a disconnection loop, and hence enhance GB migration.