Mechanical Strength and Failure Characteristics of Cast Mg-9 pctAl-1 pctZn Alloys Produced by a Heated-Mold Continuous Casting Process: Tensile Properties
- 190 Downloads
The mechanical properties and failure characteristics of a cast Mg alloy (AZ91: Mg-Al8.9-Zn0.6-Mn0.2) produced by a heated-mold continuous casting process (HMC) are investigated. In a modification of the original HMC process, the cooling of the liquid alloy by direct water spray is carried out in an atmosphere of high-purity argon gas. The HMC-AZ91 alloy exhibits excellent mechanical properties (high strength and high ductility) that are about twice as high as those for the same alloy produced by conventional gravity casting. The increased material strength and ductility of the HMC sample are attributed to nanoscale and microscale microstructural characteristics. The fine grains and tiny spherical eutectic structures (e.g., Mg17Al12 and Al6Mn) distributed randomly in the matrix of the HMC alloy result in resistance to dislocation movement, leading to high tensile strength. Basal slip on (0001) planes in the relatively organized crystal orientation of the HMC alloy, as well as grain boundary sliding through tiny spherical eutectic structures, results in high ductility. Details of the failure mechanism under static loading in the HMC alloy are also discussed using failure models.
KeywordsCrystal Orientation Basal Slip Squeeze Casting Gravity Casting AZ91 Sample
This work was supported by a grant (Grant-in-Aid for Scientific Research (C), 2014) from the Japanese Government (Ministry of Education, Science, Sports and Culture) and Ehime University.
- 2.A. Lohmüller, M. Scharrer, R. Jenning, M. Hilbinger, and M. Hartmann: Proc. 6th Int. Conf. Mg Alloy and Appl. Wolfsburg, Nov. 2003, pp. 738–43.Google Scholar
- 7.W.D. Callister Jr.: Materials Science and Engineering, 7th ed., Wiley, Hoboken, NJ, 2007, p. 378.Google Scholar
- 11.R.W. Hertzberg: Deformation and Fracture Mechanics of Engineering Materials, 4th ed., Wiley, New York, 1996, pp. 89–92.Google Scholar
- 16.F. Hnilica, V. Očenášek, I. Stulíková, and B. Smola: Kov Mater., 2005, vol. 43, pp. 300–16.Google Scholar
- 20.A. Ohno: Solidification, 1st ed., Springer, Germany. 1987, pp. 113–18.Google Scholar
- 21.Z.M. Zhang, T. Lii, C.J. Xu, and X.F. Guo: Acta. Metall. Sin. (Engl. Lett.), 2008, vol. 21, pp. 275–81.Google Scholar
- 24.A. Munitz, C. Cotler, H. Shaham, and G. Kohn: Weld. J., 2000, vol. 79, pp. 202s–208s.Google Scholar
- 34.M.M. Avedesian, and H. Baker: ASM Specialty Handbook, Magnesium and Magnesium Alloys, 1st ed., Materials Information Society, ASM International, 1999, p. 67.Google Scholar