Effect of segregated Al on $\left\{{10\bar 12} \right\}$ { 10
- PDF / 1,771,372 Bytes
- 13 Pages / 584.957 x 782.986 pts Page_size
- 14 Downloads / 184 Views
Motohiro Yuasa and Yasumasa Chino Structural Materials Research Institute, National Institute of Advanced Industrial Science and Technology, Nagoya 463-8560, Japan
Mamoru Mabuchi Department of Energy Science and Technology, Graduate School of Energy Science, Kyoto University, Kyoto 606-8501, Japan (Received 17 July 2015; accepted 6 October 2015)
Molecular dynamics simulations of compression deformation of ½1120-textured 2-dimensional polycrystalline pure Mg, Mg–0.1 at.%Al, and Mg–1.0 at.%Al models were performed at 5 and 300 K. A f1011g twin nucleated before formation of a f1012g twin in the simulations at 5 K, while a f1011g twin nucleated after formation of a f1012g twin in the simulations at 300 K. The formation of a f1011g twin was the result of the glide of pyramidal Æc 1 aæ partial 11g twin formation was suppressed at the sites around the dislocations of 1=6f1011g½2023. f10 Al atoms because the strong Mg–Al bond suppresses atomic shuffling. However, formation was not suppressed at the sites away from the Al atoms because the effect of strong Mg–Al bond is short range. On the other hand, because f1012g twinning requires the simultaneous glide of zonal dislocations, Al inevitably suppressed f1012g twinning.
I. INTRODUCTION
Magnesium and its alloys are attracting much attention as structural light metallic materials for reducing environmental load by improving the fuel efficiency of vehicles, airplanes, and so on.1 It is desirable to improve the ductility and strength of Mg for more applications in automotive and aerospace components, and so on. In crystals five independent slip systems are required to accommodate general homogeneous deformation according to the von Mises criterion. However, Mg has fewer slip systems because of its anisotropic hexagonal close packed (hcp) structure, in which basal Æaæ slips with only two independent slip systems are rather active. Fewer slip systems result in enhanced twinning deformation.2 Mg has three major twinning modes: f1012gÆ1011æ, 11gÆ10 12æ and f1013gÆ3032æ.2–6 In particular, the f10 f1012g twin and the f1011g twin strongly affect the mechanical properties of Mg.4,7–10 The f1012g twin is known as the Æcæ-axis extension twin and easily occurs when a grain is deformed in tension along the Æcæ axis, while the f10 11g twin is called the Æcæ-axis contraction twin and occurs when a grain is deformed in compression along the Æcæ-axis. f1012g twins increase uniform
Contributing Editor: Jörg F. Löffler a) Address all correspondence to this author. e-mail: [email protected] DOI: 10.1557/jmr.2015.330 J. Mater. Res., Vol. 30, No. 23, Dec 14, 2015
elongation and cause work hardening.4,7,8 f1011g twins absorb dislocations9,10 and f1011g f1012g double twins cause premature fracture.5,7–11 Thus, the twins affect the mechanical properties of Mg, and it is important to understand the twinning characteristics for development of high-performance Mg alloys. Experimental investigations have shown that twinning strongly depends on the grain si
Data Loading...
