Abstract: (5940 Views)
Microstructure evolution and mechanical properties of Zn-22Al alloy after post-ECAP natural/artificial aging were investigated. A homogenization treatment was applied to the casting samples. In addition, after preparing the samples for the ECAP, secondary homogenization treatment was done and then the samples quenched in the water to form a fine grain structure. After 8 passes of ECAP, some ECAPed samples were naturally aged and some ECAPed samples were artificially aged. Natural aging after 8 passes of ECAP showed that Zn-22Al alloy has a quasi-stable microstructure because limited grain growth occurred. Two-phase structure of Zn-22Al alloy prevented excessive grain growth after natural aging. On the other hand, artificial aging after 8 passes of ECAP caused a relatively much grain growth took place. In shorter times of artificial aging, the grain growth rate is faster due to the high surface energy of grain boundaries. On the contrary, as the time of artificial aging increased, the surface energy of grain boundaries decreased, which leads to a decrease in the grain growth rate. In addition, texture evolution was studied after aging artificial. Therefore, the main texture of α and η phases was determined.
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Highlights:
- The natural aging at room temperature after 8 passes of ECAP showed that the microstructure is not stable during isothermal storage. In the other words, the microstructure is quasi-stable at room temperature after ECAP process.
- It is necessary to mention that grain growth during storage at room temperature was limited due to the two-phase structure of the alloy that prevents each other from excessive growing.
- In the short time of artificial aging after 8 passes of ECAP, the grain growth rate is higher than in the long time of artificial aging.
- After 128 h of aging at 250 °C, the main texture of α phase was Copper {1 1 2} <1 1 1>. On the other hand, the components of P and Y were the main texture of η phase.
Type of Study:
Research Paper |
Subject:
Polymers