Influence of calcium addition on the superplastic-like behavior of extruded Al-Al 3 Ni eutectic alloy
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Aging Condition
Test Temperature (K)
YS* (MPa)
UTS* (MPa)
Elongation (Pct)
SHE* n
Alloy 648
underaged
293 77 (Pct change**) 293 77 (Pct change) 293 77 (Pct change) 293 77 (Pct change)
400 458 (15) 409 473 (16) 422 442 (5) 426 472 (11)
440 514 (17) 436 528 (21) 539 638 (18) 514 620 (21)
9.3 4.7 (250) 8.4 3.7 (256) 5.7 17.3 (204) 7.7 9.1 (18)
0.151 0.168 (11) 0.087 0.141 (62) 0.188 0.213 (13) 0.121 0.174 (44)
overaged Alloy 644
underaged overaged
*YS: yield strength, UTS: ultimate tensile strength, and SHE: strain-hardening exponent. **(Pct change) 5 {(77 K 2 293 K)/(293 K)} 3 (100 pct).
5. D. Webster: Metall. Trans. A, 1987, vol. 18A, pp. 2181-93. 6. K.T.V. Rao, H.F. Hayashigatani, W. Yu, and R. O. Ritchie: Scripta Metall., 1988, vol. 22, pp. 93-98. 7. K.V. Jata and E.A. Starke, Jr.: Scripta Metall., 1988, vol. 22, pp. 1553-56. 8. K.S. Shin, S.S. Kim, and E.W. Lee: TMS Fall Meeting, Chicago, IL, 1988. 9. Y.B. Xu, L. Wang, Y. Zhang, Z.G. Wang, and Q.Z. Hu: Metall. Trans. A, 1991, vol. 22A, pp. 723-29. 10. J.A. Wagner and R.P. Gangloff : Scripta Metall., 1992, vol. 26, pp. 1779-84. 11. S.C. Park and K.S. Shin: Proc. 2nd Pacific Rim Int. Conf. on Advanced Materials and Processing, K.S. Shin. J.K. Yoon, and S.J. Kim, eds., Korean Institute of Metals and Materials, Seoul, 1995, pp. 2235-40. 12. N.J. Kim, D.K. Skinner, K. Okazaki, and C.M. Adam: in AluminumLithium Alloys III, C. Baker, P.J. Gregson, S.J. Harris, and C.J. Peels, eds., TMS-AIME, Warrendale, PA, 1981, pp. 78-84.
Influence of Calcium Addition on the Superplastic-Like Behavior of Extruded Al-Al3Ni Eutectic Alloy J.Y. UAN, T.S. LUI, and L.H. CHEN Enhancing the strain rate of superplastic deformation is an important subject. Strain rates in excess of 1022 s21 are necessary to make the superplastic forming technique appropriate for practical applications. To achieve this goal, alloying with a minor active element such as calcium may represent a viable approach. Al-Al3Ni and Al-X-Ni and AlNi-X alloys, where X 5 Mg, Mn, etc., have an acceptable strength owing to the presence of hard eutectic Al3Ni particles. Studies regarding the mechanical properties of cast[1,2] or extruded[3,4] Al-Ni alloy have also indicated that this alloy may be a potential structural material. Some superplastic studies of this alloy system had been made.[5,6] J.Y. UAN, Postdoctor, Department of Materials Science and Engineering, National Cheng Kung University, Tainan, Taiwan 70101, Republic of China. T.S. LUI and L.H. CHEN, Professors, are with the Department of Materials Science and Engineering, Cheng Kung University, Tainan, Taiwan 70101, Republic of China. Manuscript submitted November 23, 1998. 2258—VOLUME 30A, AUGUST 1999
For example, the experimental data from Otsuka et al.[5] reveal that Al-Al3Ni eutectic alloy possesses ,170 pct strain at 3.3 3 1023 s21 strain rate and 500 8C temperature. Under similar conditions, our experimental results[7,8] show an elongation of 240 to 300 pct at 500 8C. The preceding findings are significant, because the required elongation in s
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