Age hardening response of AA7108A investigated by means of Synchrotron-based X-ray Absorption Spectroscopy (XAS) measurements
| Autor: | Chatree Saiyasombat, Chijioke Kenneth Akuata, Christoph Altenbach, Daniela Zander, Piyada Suwanpinij, Christian Schnatterer |
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| Rok vydání: | 2019 |
| Předmět: |
010302 applied physics
X-ray absorption spectroscopy Materials science Absorption spectroscopy Precipitation (chemistry) Mechanical Engineering Alloy Analytical chemistry 02 engineering and technology engineering.material 021001 nanoscience & nanotechnology Condensed Matter Physics 01 natural sciences XANES Precipitation hardening Mechanics of Materials Phase (matter) 0103 physical sciences engineering General Materials Science Solvus 0210 nano-technology |
| Zdroj: | Materials Science and Engineering: A. 747:42-52 |
| ISSN: | 0921-5093 |
| Popis: | Enhanced strengthening achieved during age hardening of 7xxx alloys, necessitated the need to study the age hardening response of Cu-free AA7108A wire, as a potential material for automobile fastener production. Age hardening response was investigated by means of Synchrotron-based X-ray Absorption Spectroscopy (XAS) measurements. Linear combination fitting (LCF), using XANES spectra of Zn K-edge showed the gradual removal of Zn atoms from the aluminum matrix of the T4 condition (where Zn is in solution and in GP zones), when subjected to one-step artificial aging treatment at 130 °C and 200 °C, respectively. The reduction of matrix Zn during aging at 130 °C is mainly due to the precipitation of the semi-coherent η’ phase, whose number density increased with increasing aging time. η’ phase is the major phase responsible for hardness and electrical conductivity increase during aging at 130 °C. Reduction of matrix Zn concentration during aging at 200 °C is due to the formation and coarsening of the incoherent η-MgZn2 phase. This resulted in a dramatic decrease in hardness and an increasing trend in the electrical conductivity during aging at 200 °C. Calorimetric study revealed that natural aging occurred at room temperature after solution treatment, and GP zone solvus is found to be below 130 °C. In addition, precipitation of the η’ phase at 130 °C is retarded, due to reduced concentration of vacancies, attributed to the presence of Zirconium (Zr) in the alloy. |
| Databáze: | OpenAIRE |
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