TY - JOUR
T1 - Creep behavior of pure magnesium and Mg-Al alloys in active environments
AU - Unigovski, Ya
AU - Keren, Z.
AU - Eliezer, A.
AU - Gutman, E. M.
N1 - Funding Information:
This work was supported by Portuguese national funds from the Foundation for Science and Technology of the Portuguese Government, [Understanding Underground Biodiversity: Studies in Azorean Lava Tubes (reference PTDC/AMB/70801/2006]. CR and IRA were funded by the Regional Fund for Science and Technology and Pro-Emprego program of the Regional Government of the Azores, Portugal [M3.1.7/F/013/2011 and M3.1.7/F/030/2011, respectively]. FR and PB were funded by the Foundation for Science and Technology of the Portuguese Government [FCT-PTDC/BIA-BIC/119255/2010]. This work was also supported by the Cave Conservancy of the Virginias, the Graduate Research Allocation Committee at UNM Biology, UNM Biology Grove Scholarship, the Student Research Allocation Committee at UNM, the National Speleological Society, the New Mexico Space Grant Consortium, and Kenneth Ingham Consulting (USA).
Funding Information:
The authors wish to thank the Montanheiros association (http://www.montanheiros.com), especially Fernando Pereira, Maria João Leal and Paulino Costa, and Airidas Dapkevicius, Kenneth Ingham, Pedro Cardoso, Ana Rita Varela, Clara Gaspar, Ali Ghadimi, John Craig and Guida Pires for help during field and lab work. Island maps and surface precipitation data were kindly provided by the Center of Climate, Meteorology and Global Changes of the University of the Azores/Projecto CLI-MAAT Ac¸ores e ESTRAMAR (MAC/3/C177) supported by the European Union through the MAC Transnational Program of Co-operation – Madeira-Azores-Canaries. We acknowledge support from the UNM Molecular Biology Facility, which is funded by NIH (grant no. P20GM103452). The authors would like to thank the referees for their valuable comments which helped to improve the manuscript.
PY - 2005/5/25
Y1 - 2005/5/25
N2 - Environment-enhanced creep, which we have called "corrosion creep" (CC), was investigated in pure Mg and die-cast AZ91D, AM50 and AS21 alloys in a borate buffer solution and 3.5% NaCl at room temperature. In contrast to the data in the air demonstrating only the first stage of creep process, in corrosive solutions, secondary and tertiary creep due to the plasticization effect of the solution was observed. The lifetime of pure Mg increases by one order of magnitude in the buffer solution in comparison with that in 3.5% NaCl. Elongation-to-fracture in the former was approximately twice as high as that in NaCl, probably, due to hydrogen embrittlement in the latter. In corrosive solutions, the creep life and elongation-to-fracture of Mg alloys decreases with increasing aluminum content from 2.3 to 8.4% in AS21, AM50 and AZ91D alloys. Cracking and final creep-rupture of pure Mg originate in a transcrystalline manner in comparison with intercrystalline fracture of the alloys. Cracks are observed in pure Mg at the primary creep stage, but their depth and amount are relatively small. The effect of environment on the creep behavior of magnesium is connected, mainly, with plasticization of metal assisted by chemical reactions. Also, anodic dissolution of Mg is enhanced by creep stress.
AB - Environment-enhanced creep, which we have called "corrosion creep" (CC), was investigated in pure Mg and die-cast AZ91D, AM50 and AS21 alloys in a borate buffer solution and 3.5% NaCl at room temperature. In contrast to the data in the air demonstrating only the first stage of creep process, in corrosive solutions, secondary and tertiary creep due to the plasticization effect of the solution was observed. The lifetime of pure Mg increases by one order of magnitude in the buffer solution in comparison with that in 3.5% NaCl. Elongation-to-fracture in the former was approximately twice as high as that in NaCl, probably, due to hydrogen embrittlement in the latter. In corrosive solutions, the creep life and elongation-to-fracture of Mg alloys decreases with increasing aluminum content from 2.3 to 8.4% in AS21, AM50 and AZ91D alloys. Cracking and final creep-rupture of pure Mg originate in a transcrystalline manner in comparison with intercrystalline fracture of the alloys. Cracks are observed in pure Mg at the primary creep stage, but their depth and amount are relatively small. The effect of environment on the creep behavior of magnesium is connected, mainly, with plasticization of metal assisted by chemical reactions. Also, anodic dissolution of Mg is enhanced by creep stress.
KW - Borate buffer solution
KW - Corrosion creep
KW - Creep life
KW - Magnesium alloys
KW - NaCl
KW - Pure magnesium
UR - http://www.scopus.com/inward/record.url?scp=18944402475&partnerID=8YFLogxK
U2 - 10.1016/j.msea.2005.03.017
DO - 10.1016/j.msea.2005.03.017
M3 - Article
AN - SCOPUS:18944402475
SN - 0921-5093
VL - 398
SP - 188
EP - 197
JO - Materials Science and Engineering: A
JF - Materials Science and Engineering: A
IS - 1-2
ER -