Multi-scale study of microstructure evolution in hot extruded nano-sized TiB 2 particle reinforced aluminum composites Z. Chen a , G.A. Sun b , Y. Wu a , M.H. Mathon c , A. Borbely d , D. Chen a , G. Ji e , M.L. Wang a, ⁎, S.Y. Zhong f, ⁎, H.W. Wang a,f a State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, Shanghai 200240, PR China b Institute of Nuclear Physics and Chemistry, Mianyang 621900, PR China c Science of Matter Direction, IRAMIS, CEA/Saclay, 91191 Gif-sur-Yvette, France d SMS Materials Center and LGF UMR 5307, Ecole des mines de Saint Etienne, 158, cours Fauriel, 42023 Saint Etienne, France e Unité Matériaux et Transformations, CNRS UMR 8207, Université Lille 1, Villeneuve d'Ascq 59655, France f School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, PR China HIGHLIGHTS • The microstructures and textures of in- situ TiB 2 /Al composites are character- ized quantitatively. • The effects of TiB 2 particles on the (sub-)grain boundaries and disloca- tions are characterized and discussed. • The dynamic recovery and recrystalliza- tion mechanisms of in-situ TiB 2 /Al com- posites are studied. GRAPHICAL ABSTRACT abstract article info Article history: Received 20 October 2016 Received in revised form 20 December 2016 Accepted 22 December 2016 Available online 23 December 2016 The microstructural evolution of in-situ TiB 2 nano-particle reinforced AlZnMgCu composites during hot extrusion was investigated from micro to macro scales by a combination of various techniques, including neutron and syn- chrotron X-ray diffraction, optical microscopy, scanning and transmission electron microscopy and electron backscatter diffraction (EBSD). The development of microstructure has shown a bimodal grain structure with dis- tinctive spatial distributions of TiB 2 particles: the elongated coarse grain structure with smaller dispersed parti- cles and the fine grains mixed with clusters of relatively larger particles. The particle stimulated nucleation occurs at large particle clusters, resulting in recystallized (sub)micron sized fine grains. The dispersed smaller particles are observed to promote dislocation generation and to prohibit recovery. They are shown to reduce the misori- entation of low angle grain boundaries due to the pinning effects on independent dislocations, which also lead to the suppression of dynamic recovery and increase of driving force for dynamic recrystallization. Quantitative tex- ture analysis combined with neutron diffraction and EBSD has exhibited the development of a strong 〈111〉 and 〈001〉 dual fiber texture, and both texture volume fractions are changing with the particle content. In ad- dition, the synchrotron diffraction experiments have shown that dislocation density increases with the particle content in both texture components. The microstructure evolution is the result from a complex process of Keywords: Nano-sized TiB 2 particles Metal matrix composites Neutron diffraction Plastic deformation Dislocation Recovery & Recrystallization Materials and Design 116 (2017) 577–590 ⁎ Corresponding authors. E-mail addresses: mingliang_wang@sjtu.edu.cn (M.L. Wang), shengyi.zhong@sjtu.edu.cn (S.Y. Zhong). http://dx.doi.org/10.1016/j.matdes.2016.12.070 0264-1275/© 2016 Elsevier Ltd. All rights reserved. Contents lists available at ScienceDirect Materials and Design journal homepage: www.elsevier.com/locate/matdes