Pan American Materials Congress: Nanocrystalline and Ultra-fine Grain Materials and Bulk Metallic Glasses: Microstructure Evolution
Sponsored by: Third Pan American Materials Congress Organizing Committee
Program Organizers: Terence Langdon, University of Southern California; Megumi Kawasaki, Oregon State University; Roberto Figueiredo, Federal University of Minas Gerais; Jose-Maria Cabrera, Universidad Politecnica de Catalunya

Wednesday 10:10 AM
March 1, 2017
Room: Marina F
Location: Marriott Marquis Hotel

Session Chair: Shima Sabbaghianrad, University of Southern California; Laszlo Toth, Université de Lorraine

10:10 AM  
Quantitative Modeling of Grain Fragmentation during Severe Plastic Deformation Featuring Grain Size Distribution, Texture, Strain Hardening, and Disorientation Distribution: Laszlo Toth1; 1Université de Lorraine
    A quantitative model was presented in 2010 by Toth et al. [Acta Materialia, 58 (2010) 1782] for predicting grain fragmentation during severe plastic deformation. The approach is based on the lattice rotation induced lattice curvature, thus, on the rotation of the crystals induced by the plastic strain. This model so far the most complete for predicting grain fragmentation because it is able to predict quantitatively in a single frame the evolution of the grain size distribution, the crystallographic texture, strain hardening, and disorientation angle (and axis) distribution. Several applications have proved the predictive capacity of the model. The present work report about the latest achievements of the lattice-curvature model and presents the software package which will be open for general use by the SPD community.

10:30 AM  
Continuous Dynamic Recovery in Pure Aluminum Deformed to High Strain by Accumulative Press Bonding: Sajjad Amirkhanlou1; Mostafa Ketabchi2; Nader Parvin3; Fernando Carreño4; 1Brunel University London; 2Amirkabir University of Technology ; 3Amirkabir University of Technology; 4CENIM-CSIC
    Microstructural evolution and mechanical properties of AA1050 aluminum alloy, prepared by accumulative press bonding, have been investigated by means of sophisticated analytical tools, including STEM and EBSD. The results revealed that continuous dynamic recovery was dominant mechanism in grain refinement, and resulted in formation of nano/ultrafine grains with average diameter of 450 nm in pressing direction and 320 nm in transverse direction. By increasing strain during APB process, the mean misorientation angle and the fraction of high angle boundaries increased and reached a saturation value of ~35˚ and ~78%, respectively. When strain increased during APB process, the tensile strength of the aluminum improved and reached 180 MPa after 14 cycles and the elongation dropped dramatically at the first cycle and then increased slightly. Strengthening in APB processed aluminum was attributed to strain hardening by dislocation accumulation dominant in primary cycles, and grain refinement which was dominant in final cycles.