J. Mater. Sci. Technol. ›› 2018, Vol. 34 ›› Issue (2): 257-264.DOI: 10.1016/j.jmst.2017.11.018

• Orginal Article • Previous Articles     Next Articles

Bimodal microstructure - A feasible strategy for high-strength and ductile metallic materials

Min Zhaab, Hong-Min Zhangb, Zhi-Yuan Yub, Xuan-He Zhangb, Xiang-Tao Mengb, Hui-Yuan Wangab(), Qi-Chuan Jiangab   

  1. aState Key Laboratory of Automotive Simulation and Control, Jilin University, Changchun 130025, China
    bKey Laboratory of Automobile Materials of Ministry of Education & School of Materials Science and Engineering, Nanling Campus, Jilin University, Changchun 130025, China;
  • Received:2017-06-20 Revised:2017-08-26 Accepted:2017-08-31 Online:2018-02-10 Published:2018-02-10

Abstract:

Introducing a bimodal grain-size distribution has been demonstrated an efficient strategy for fabricating high-strength and ductile metallic materials, where fine grains provide strength, while coarse grains enable strain hardening and hence decent ductility. Over the last decades, research activities in this area have grown enormously, including interesting results on fcc Cu, Ni and Al-Mg alloys as well as steel and Fe alloys via various thermo-mechanical processing approaches. However, investigations on bimodal Mg and other hcp metals are relatively few. A brief overview of the available approaches based on thermo-mechanical processing technology in producing bimodal microstructure for various metallic materials is given, along with a summary of unusual mechanical properties achievable by bimodality, where focus is placed on the microstructure-mechanical properties and relevant mechanisms. In addition, key factors that influencing bimodal strategies, such as compositions of starting materials and processing parameters, together with the challenges this research area facing, are identified and discussed briefly.

Key words: Nanocrystalline and ultrafine-grained metals, Mechanical milling, Severe plastic deformation, Bimodal microstructure, Strength and ductility