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Transient and steady-state creep characteristics of Transformations in Al-Zn Binary Alloys |
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PP: 21-33 |
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Author(s) |
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M. Yousf Salem,
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Abstract |
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| Transient and steady - state creep tests were studied under different applied stresses ranging from 12.236 to 14.275 MPa from 523 K to 633 K for Binary (Zn -28.5 Al based) Alloys. The transient creep is described by tr = tn, where tr and t are the transient creep strain and time. The parameters and n were calculated and found to change from 3.73 to -1.791 and 0.227 to 0.718 respectively. The alloy showed increase in the creep parameters and n. The exponent have values 0.53 - 0.9,the activation energy of transient creep are and 63.8 KJ/ mole and 66.8 KJ/ mole in Low and high temperature range respectively. Also, the steady state creep was investigated in the same temperature range under same stresses .The results of creep characteristics show two deformation regions (below and above 543 K). The strain rate sensitivity parameter (m) has been found to increase by increasing the working temperature up to about 0.53 for the alloy. The activation energies of steady state creep of the alloy have been found to be 76.7 and 79.72 kJ/mol, in the low and high temperature regions respectively (below and above 543 K), characterizing grain boundary diffusion. Metallographic observations and X-ray analysis have been confirmed that grain boundary sliding (GBS) assimilation by dislocation motion is the aim mode of deformation |
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