SUMMARY Strong and ductile materials are required for multiple structural applications. In this

1. The Mechanism of Grain Refinement in hcp Metals and Alloys with Severe Plastic Deformation Leading to Nanoscale Microstructures , Micheal E. Kassner, University of Southern California, DMR 0501605 Room T e =0.3 25% 3 reduction 5.2 mm Strained material Annealed material 3.9 mm Room temperature 327ºC 327ºC 327ºC ARB 1 ARB 2 ARB 3 e = 1.97 e e Stacking = 3.61 = 5.25 Stacking T T T 1.9 mm RD TD Fig. 2 Pure Zr-99.98% ND Annealed material 100 mm Fig. 1 Accumulative roll bonding process RD SUMMARY Strong and ductile materials are required for multiple structural applications. In this work tough Zr is fabricated by accumulative roll bonding (ARB). This technique consists on several cycles of rolling, cutting and stacking, as described in Figure 1. The initial and processed microstructures are illustrated in Fig. 2. Strength is increased by grain refinement. A final grain size of 400 nm is achieved. The mechanical behavior of the processed samples is represented in Fig. 3. ARB leads to a dramatic increase in the strength without a significant decrease in ductility. Zr has been traditionally applied in the nuclear industry as a fuel rod material but recent studies are confirming its extraordinary biocompatibility. ARB 1 5 mm ARB 2 5 mm ARB 3 Fig. 3 Mechanical behavior 5 mm L. Jiang, O.A. Ruano, M.E. Kassner, M.T Pérez-Prado, “Bulk Ultrafine Grained Zr by Accumulative Roll Bonding. J. Metals,6 (2007) 42-45. L. Jiang, M.T. Pérez-Prado, P. Gruber, E. Arzt, O.A. Ruano, M.E. Kassner,”Texture Microstructureand Mechanical Properties of Ultrafine Grained Zr Fabricated by Accumulative Roll Bonding”, submitted to Acta Mater, 2007

2. Micheal E. Kassner, University of Southern California, DMR 0501605 Broader impact • This project has been the involves a collaboration between USC and CENIM, • (National Center for Metals Research), CSIC, Spain. Supporting Spanish funds • awarded by the Madrid State Government (MAT2005-24523-E, 2006/60M067) and the • Spanish Ministry of Science and Technology (MAT2006-11202-E). • EDUCATION • Ling Jiang is carrying out his PhD dissertation in ARB of Zr alloys as part of a joint • PhD program between USC and CENIM. His coadvisors are Prof. M.E. Kassner (USC) • and M.T. Pérez-Prado (CENIM). • Ms. Rocío Villalvilla received her MSc degree in Materials Engineering at the • Universidad Complutense de Madrid, Spain. Her thesis topic was “Fabrication of • Ultrafine Grained Zr by Accumulative Roll Bonding”. • TECHNOLOGY TRANSFER • Spanish Patent Nº 200600492 was granted in 2007 for “Processing ultrafine • grained materials by severe rolling” • OUTREACH • This research was disseminated in the graduate course • Materials Selection AME 588 at USC.