DOI QR코드

DOI QR Code

Effects of Mg and Cu Additions on Superplastic Behavior in MA Aluminum Alloys

  • Han, Chang-Suk (Dept. of ICT Automotive Engineering, Hoseo University) ;
  • Jin, Sung-Yooun (Dept. of ICT Automotive Engineering, Hoseo University) ;
  • Bang, Hyo-In (Dept. of ICT Automotive Engineering, Hoseo University)
  • Received : 2018.06.19
  • Accepted : 2018.07.13
  • Published : 2018.08.27

Abstract

MA Al alloys are examined to determine the effects of alloying of Mg and Cu and rolling on tensile deformation behavior at 748 K over a wide strain rate range($10^{-4}-10^3/s$). A powder metallurgy aluminum alloy produced from mechanically alloyed pure Al powder exhibits only a small elongation-to-failure(${\varepsilon}_f$ < ~50%) in high temperature(748 K) tensile deformation at high strain rates(${\acute{\varepsilon}}=1-10^2/s$). ${\varepsilon}_f$ in MA Al-0.5~4.0Mg alloys increases slightly with Mg content(${\varepsilon}_f={\sim}140%$ at 4 mass%). Combined addition of Mg and Cu(MA Al-1.5%Mg-4.0%Cu) is very effective for the occurrence of superplasticity(${\varepsilon}_f$ > 500%). Warm-rolling(at 393-492 K) tends to raise ${\varepsilon}_f$. Lowering the rolling-temperature is effective for increasing the ductility. The effect is rather weak in MA pure Al and MA Al-Mg alloys, but much larger in the MA Al-1.5%Mg-4.0%Cu alloy. Additions of Mg and Cu and warm-rolling of the alloy cause a remarkable reduction in the logarithm of the peak flow stress at low strain rates (${\acute{\varepsilon}}$< ~1/s) and sharpening of microstructure and smoothening of grain boundaries. Additions of Mg and Cu make the strain rate sensitivity(the m value) larger at high strain rates, and the warm-rolling may make the grain boundary sliding easier with less cavitation. Grain boundary facets are observed on the fracture surface when ${\varepsilon}_f$ is large, indicating the operation of grain boundary sliding to a large extent during superplastic deformation.

Keywords

References

  1. I. E. Anderson and J. C. Foley, Surf. Interface Anal., 31, 599 (2001). https://doi.org/10.1002/sia.1087
  2. D. Jiang and T. Imai, Mater. Chem. Phys., 80, 15 (2003). https://doi.org/10.1016/S0254-0584(02)00447-9
  3. M. Besterci, O. Velgosova and L. Kova , Mater. Lett., 54, 124 (2002). https://doi.org/10.1016/S0167-577X(01)00549-3
  4. T. Ishikawa, N. Yukawa, Y. Yoshida and K. Murakami, J. Mater. Proc. Tech., 113, 632 (2001). https://doi.org/10.1016/S0924-0136(01)00647-1
  5. T. Fujii, S. Sodeoka and K. Ameyama, J. Jpn. Inst. Light Metals, 47, 329 (1997). https://doi.org/10.2464/jilm.47.329
  6. T. G. Nieh, P. S. Gilman and J. Wadsworth, Scripta Metall., 19, 1375 (1985). https://doi.org/10.1016/0036-9748(85)90070-5
  7. T. R. Bieler, T. G. Nieh, J. Wadsworth and A. K. Mukherjee, Scripta Metall., 22, 81 (1988). https://doi.org/10.1016/S0036-9748(88)80310-7
  8. K. Higashi, T. Okada, T. Mukai and S. Tanimura, Proc. Conf. on Superplasticity in Advanced Materials, ed. by S. Hori, M. Tokizane and N. Furushiro, p.569, JSRS, Osaka (1991).
  9. T. R. Bieler, S. F. Meagher, J. A. Diegel and A. K. Mukherjee, Proc. Conf. on Hot Deformation of Aluminum Alloys, ed. by T. G. Langdon, H. D. Merchant, J. G. Morris and M.A Zaidi, p.297, TMS, Warrendale (1991).
  10. M. A. Garcia-Bernal, R. S. Mishra, R. Verma and D. Hernandez-Silva, Mater. Sci. Eng., A, 534, 186 (2012). https://doi.org/10.1016/j.msea.2011.11.057