Microstructural evolution and thermal stability of 1050 commercial pure aluminum processed by high-strain-rate deformati
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Ya Dong Chena) School of Material Science and Engineering, Central South University, Changsha 410083, China
Hai Bo Hu and Tie Gang Tang Institute of Fluid Physics, China Academy of Engineering Physics, Mianyang 621900, China
Ren Rong Long and Qing Ming Zhang State Key Laboratory of Explosion Science and Technology, Beijing Institute of Technology, Beijing 100081, China (Received 4 May 2015; accepted 8 October 2015)
Microstructural and property evolution of 1050 commercial pure aluminum subjected to high-strain-rate deformation (1.2–2.3 103 s1) by split Hopkinson pressure bar (SHPB) and subsequent annealing treatment were investigated. The as-deformed and their annealed samples at 373–523 K were characterized by transmission electron microscopy (TEM) and microhardness tests. TEM observations reveal that the as-deformed sample is mainly composed of a lamellar structure, whose transverse/longitudinal average subgrain/cell sizes are 293 and 694 nm, respectively. The initial coarse grains are refined significantly. The initial lamellar grain structures are subdivided into pancake-shaped subgrains due to a gradual transition by triple junction motion at 473 K, and then a dramatic microstructural coarsening is observed at 523 K. It is suggested that annealing behavior of this dynamic loading structure is better considered as a continuous process of grain coarsening or continuous recovery. I. INTRODUCTION
Contributing Editor: Andrea Maria Hodge a) Address all correspondence to this author. e-mail: [email protected] DOI: 10.1557/jmr.2015.341
a steady plastic deformation will occur. Experimental results indicated that the grain size has a linear relationship with the inverse square root of dislocation density (Dc 5 Kq1/2).4 Plenty of research showed that there is a saturate grain size during the SPD of metallic materials.5 To refine grain further, some special methods should be developed, such as cryogenic or DPD.6,7 Ultrafine grain materials that were produced by SPD or DPD contain a large amount of dislocations and nonequilibrium grain boundaries, which result in significant increase in hardness and strength but limited stability.8–11 That is to say, such microstructures can be easily changed by recovery and recrystallization during annealing. Microstructural coarsening will inevitably weaken mechanical properties of materials, against their application as potential engineering materials. Therefore, it is essential to clarify the coincident influences of annealing treatment on the microstructural evolution, along with reducing the instabilities. 1050 commercial pure aluminum was subjected to high-strain-rate deformation with the strain rate up to 2.3 103 s1 by means of split Hopkinson pressure bar (SHPB) in this work. The effects of the high strain rate on microstructural evolution and thermal stability of 1050 commercial pure aluminum were investigated.
3502
Ó Materials Research Society 2015
Pure aluminum and aluminum alloys play a key role in modern engineering since they are the most used nonferrous materi
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