SUMMARYStrong and ductile materials are required for multiple structural applications. In thiswork tough Zr is fabricated by accumulative roll bonding (ARB). This techniqueconsists on several cycles of rolling, cutting and stacking, as described in Figure 1.

The initial and processed microstructuresare illustrated in Fig. 2. Strength is increasedby grain refinement. A final grain size of 400 nm is achieved. The mechanicalbehavior of the processed samples is represented in Fig. 3. ARB leads to a dramaticincrease in the strength without a significantdecrease in ductility.

Zr has been traditionally applied in the nuclearindustry as a fuel rod material but recent studiesare confirming its extraordinary biocompatibility.

100 m

ND

RDTD

5 m

5 m

5 m

RD

1.9 mm

Annealed material Strained material

327ºC ARB 1 =1.97

327ºC

ARB 2 =3.61

327ºC ARB 3 =5.25 Stacking Stacking

Room T 25%

reduction

Room temperature

5.2 mm

3.9 mm

=0.33

ARB 1

ARB 2

ARB 3

Fig. 1 Accumulative roll bonding process

Fig. 2 Pure Zr-99.98%

Annealedmaterial

Fig. 3 Mechanical behavior

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

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

•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.

Broader impactMicheal E. Kassner, University of Southern California, DMR 0501605