Low temperature quasi-superplasticity of ZK60 alloy prepared by reciprocating extrusion
| Autor: | Kai-jun Yang, Xue-feng Guo, Wen-peng Yang |
|---|---|
| Rok vydání: | 2012 |
| Předmět: |
Dislocation creep
Materials science Metallurgy Metals and Alloys Superplasticity Atmospheric temperature range Strain rate Geotechnical Engineering and Engineering Geology Condensed Matter Physics Grain size Deformation mechanism Materials Chemistry Grain boundary diffusion coefficient Composite material Grain Boundary Sliding |
| Zdroj: | Transactions of Nonferrous Metals Society of China. 22:255-261 |
| ISSN: | 1003-6326 |
| Popis: | Fine-grained ZK60 alloy was prepared by 2-pass reciprocating extrusion, and the low temperature superplasticity was conducted in a temperature range from 443 to 523 K and an initial strain rate ranging from 3.3×10−4 to 3.3×10−2 s−1. The results show that the alloy has an equiaxed grain structure with an average grain size of about 5.0 μm, and the sizes of broken secondary particles and precipitates are no more than 175 and 50 nm, respectively. The alloy exhibits quasi-superplasticity with a maximum elongation of 270% at 523 K and an initial strain rate of 3.3×10−4 s−1. The strain rate sensitivity m is less than 0.2 at 443 and 473 K, and it is 0.42 at 523 K. The apparent activation energies at temperature below 473 K and at 523 K are less than 63.2 and 110.6 kJ/mol, respectively. At temperature below 473 K, mainly intragranular sliding contributes to superplastic flow. At 523 K, grain boundary sliding is the dominant deformation mechanism, and dislocation creep controlled by grain boundary diffusion is considered to be the main accommodation mechanism. |
| Databáze: | OpenAIRE |
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