Effect of void defect on c -axis deformation of single-crystal Ti under uniaxial stress conditions: Evolution of tension
- PDF / 980,063 Bytes
- 8 Pages / 584.957 x 782.986 pts Page_size
- 89 Downloads / 202 Views
Department of Engineering Mechanics, State Key Laboratory of Ocean Engineering, School of Naval Architecture, Ocean and Civil Engineering, Shanghai 200240, People’s Republic of China 2 School of Aeronautics & Astronautics, Shanghai Jiao Tong University, Shanghai 200240, People’s Republic of China a) Address all correspondence to this author. e-mail: [email protected] Received: 6 May 2019; accepted: 29 August 2019
Deformation twins have a major role in the microstructure evolution of hexagonal close packed (HCP) metals. Voids are common defects in metals and have a significant impact on their properties. In this work, using molecular dynamics, a tension simulation of single-crystal titanium (Ti) with different void sizes under uniaxial stress conditions was performed. The results showed that the evolution and dominance of the f1012g twin system using the Henning potential was not consistent with the Schmid criterion when the single-crystal Ti contained void defects. From a microscopic perspective, the authors analyzed the relationship between the nucleation and growth of twins and the emission of dislocation loops. The authors found that the existence of voids not only contributes to the emission of dislocation loops but also hinders the movement of these loops. With the increase in void size, the peak dislocation density of 13 h1100i partial dislocation loops decreased. This work is helpful to further investigate the nucleation and evolution of tension twins and to form an effective growth criterion for twins to study the twinning process of HCP metals during plastic deformation.
Introduction Titanium (Ti) is one of the most widely used metals [1, 2] because of its good fracture strength [3] and ductility [4]. Owing to its hexagonal close packed (HCP) structure [5], Ti has a high tendency to engender deformation twins [6]. The twins can be divided into compression twins and tension twins according to their different loading methods. The most generally known compression twins are f1112g, f1124g, and f1011g, whereas those for tension twins are f1012g and f1121g [7, 8]. In recent years, a great deal of attention has been paid to the mechanism of deformation twins. Deformation twins are usually affected by defects, temperature, and strain rate [9]. Rawat and Mitra [10] investigated the evolution of compression twinning and dislocations of single-crystal Ti under uniaxial stress conditions using molecular dynamics. Barrett et al. [11] distinctly identified twin embryos and twin variants, calculated the twin volume fractions, and analyzed the grain evolution. Lainé and Knowles [12] showed the existence of f1124g twinning as a rare deformation twinning mode in
ª Materials Research Society 2019
coarse-grained commercial purity Ti using electron backscattered diffraction and transmission electron microscopy at room temperature. The twinning-induced plastic deformation in HCP metals, such as Mg and Ti, is usually investigated using crystal plasticity finite element simulations [13]. In the process of finite element
Data Loading...
