Hostname: page-component-586b7cd67f-vdxz6 Total loading time: 0 Render date: 2024-11-25T00:20:58.027Z Has data issue: false hasContentIssue false
  • English
  • Français

Positron lifetime and Doppler broadening study of defects in hydrogen charged Al–Mg alloys

Published online by Cambridge University Press:  31 January 2011

Xiaowei Wang ,
Yurong Zhong ,
Baoyi Wang  and
Hongyan Zhang
Xiaowei Wang*
Affiliation:
Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, People's Republic of China
Baoyi Wang
Affiliation:
Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100039, People's Republic of China
Hongyan Zhang
Affiliation:
Department of MIME, University of Toledo, Toledo, Ohio 43606
*
a) Address all correspondence to this author. e-mail: [email protected]
Get access

Abstract

The results of positron lifetime and Doppler broadening spectrum of defects in the hydrogen charged non-heat treatable 5xxx Al alloys are presented in this work. The yield stress of the sample was reduced for about 20 MPa after hydrogen was charged. A similar trend was observed in positron lifetime measurement, as the average lifetime τav descended remarkably to almost the level of Al matrix. The change in coincidence Doppler broadening (CDB) spectroscopy was also significant, exhibited by the characteristic change in CDB radio curves of a sample before and after hydrogen was charged. After hydrogen charging, there is an obvious enhancement in the high momentum region compensating dehancement in the low momentum region. This indicates the existence of hydrogen filling effect. The vacancies around the Mg atoms should be preferential filling sites for hydrogen because Mg has a strong affinity for hydrogen. The formation of an Mg–H bond parallel to a grain boundary is an important factor in weakening the grain boundary cohesion.

Keywords

AlloyHydrogenationStress/strain relationship
Type
Articles
Information
Journal of Materials Research , Volume 24 , Issue 5 , May 2009 , pp. 1791 - 1794
Copyright
Copyright © Materials Research Society 2009

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

REFERENCES

1.Polmear, I.J.: Light Alloys—Metallurgy of the Light Metals, 3rd ed. (Arnold, a division of Hodder Headline PLC, London, 1995).Google Scholar
2.ASM: Metals Handbook, Properties and Selection: Nonferrous Alloys and Special-Purpose Materials, Vol. 2, 10th ed. (ASM International, Materials Park, OH, 1990).Google Scholar
3.Zhang, H. and Senkara, J.: Resistance Welding: Fundamentals and Applications (CRC Press/Taylor & Francis Group, Boca Raton, London, New York, 2006).Google Scholar
4.Wang, X., Zhang, H., and Sun, A.: Influence of vacancy formation and Mg migration on cracking in spot welding AA5754 alloys. Mater. Sci. Forum 539–543, 433 (2007).CrossRefGoogle Scholar
5.Liu, X., Wang, X., Wang, J., and Zhang, H.: First-principles investigation of Mg segregation at Σ = 11(113) grain boundaries in Al. J. Phys: Condens. Matter 17, 1 (2005).Google Scholar
6.Liu, X., Wang, X., Wang, J., and Zhang, H.: Effect of interstitial hydrogen on cohensive strength of Al grain boundary with Mg segregation. J. Mar. Sci. Technol. 22, 135 (2006).Google Scholar
7.Adhikari, S., Lee, J., Chen, H., Jean, Y.C., and Hebert, K.R.: Injection of hydrogen and vacancy-type defects during dissolution of aluminum. ECS Transactions 1(4), 127 (2005).Google Scholar
8.Seeger, A.: The study of defects in crystals by positron annihilation. Appl. Phys. 4, 183 (1974).CrossRefGoogle Scholar
9.Nagai, Y., Murayama, M., Tang, Z., Nonaka, T., Hono, K., and Hasegawa, M.: Role of vacancy-solute complex in the initial rapid age hardening in an Al–Cu–Mg alloy. Acta Mater. 49, 913 (2001).Google Scholar
10.Huang, C-H., Ma, L., Chen, Z-Q., Wang, Z., Wang, X., and Zhang, H.: An experimental study of Mg aggregation in AA5754 alloys by positron annihilation spectroscopy. Chin. Phys. Lett. 24, 546 (2007).Google Scholar