CONCLUSIONS We have determined the self-affine parameters of the fracture surface of a cast aluminum alloy. The parallel and perpendicular out-of-plane roughness exponents were determined with values of 0.78 and 0.79, respectively. The roughness exponent of the arrested crack front was also determined, with a value of 0.79. It was corroborated that the correlation length is in all the cases related to the size of the largest heterogeneities present in the complex microstructure. The analysis of the crack paths in aluminum foil as developed in 2D mode I loading allowed the determination of the respective self-affine parameters. It was found that the roughness exponent has a value of 0.67 for both the parallel and transverse direction of propagation with respect to the rolling direction. The anisotropy of the microstructure has an observable effect in the correlation length whereas the roughness exponent is apparently unaffected by this condition. ACKNOWLEDGEMENTS Author express their gratitude to E. Sánchez, E. Reyes, O. Garza, I. Suárez, L. Cruz, R. Colás and E. Velasco, the financial support of the Consejo Nacional de Ciencia y Tecnología and the UANL through the PAICYT program is also gratefully acknowledged. REFERENCES 1. M. E. Eberhart, Scientific American, p. 44-51, Oct. 1999. 2. Hellemans, Science Vol. 281, p. 943-944, 14 August 1998. 3. MRS Bulletin, Vol. 25, No. 5, May 2000. 4. J.W. Hutchinson and A. G. Evans, Acta materialia Vol. 48 p. 125-135, 2000. 5. M. Marder and J. Fineberg, Physics Today Vol. 49, p. 24, 1996. 6. E. Bouchaud, J. Phys.:Condens. Matter Vol. 9, p. 4319-4344, 1997 and references therein. 7. A. Balankin, Engineering Fracture Mechanics Vol. 57, p. 135-203, 1997 and references therein. 8. B.B. Mandelbrot, Passoja, Paullay, Nature Vol 308 19 April 1984. 9. L. de Arcangelis, S. Redner, H.J. Herrmann, Journal de Physique Lettres 46, p. 585-590, 1985. 10. E. Bouchaud, G. Lappasset, J. Planes and S. Naveos, Phys. Rev. B, Vol 48, p. 2917 ,1993. 11. K. J. Maloy, A. Hansen, E. L. Hinrichsen and S. Roux, Phys. Rev. Lett., Vol. 68, p. 213-215, 1992. 12. X. Zhang, M.A. Knackstedt, D.Y.C. Chan and L. Paterson, Europhysics Letters, Vol. 34, p. 121-126, (1996). 13. J. Feder, Fractals, Plenum Press, New York, 1988. 14. M. Hinojosa, J. Aldaco, U. Ortiz and V. González, Aluminum Transactions Vol. 3, p.53-57, 2000. 15. P. Daguier, B. Nghiem, E. Bouchaud and F. Creuzet, Phys. Rev. Lett. Vol 78, p. 1062, 1997. 16. P. Daguier, Ph. D. Thesis, Paris University, Paris, 1997. 17. M. Hinojosa, E. Bouchaud y B. Nghiem, MRS Symp. Proc. Vol. 539, p. 203-208, 1999. 18. J. Aldaco, F.J. Garza, M. Hinojosa, MRS Symp. Proc. Vol. 578, p. 351-356, 2000. 19. M. Hinojosa, J. Aldaco, U. Ortiz and J.A. González, Euromat 2000, p. 1469-1474, 2000. 20. E. Reyes, Masters Thesis, Universidad Autónoma de Nuevo León, México (in Spanish), 1999. 21. J. Schmittbuhl, J. P. Vilotte and S. Roux, Phys. Rev. E, vol. 51, p. 131, 1995.
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