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Metallic Materials, 2017
Impression creep behavior of as-cast Mg-xSi alloys (x = 0.5, 0.8, 1.2 wt.%) was studied under she... more Impression creep behavior of as-cast Mg-xSi alloys (x = 0.5, 0.8, 1.2 wt.%) was studied under shear modulus-normalized stress values ranging from 0.009 to 0.016 at temperatures between 398 and 491 K. The results show that creep properties of these alloys are improved with increasing Si content under all the applied loads and temperatures, and Mg-1.2Si alloy has minimum creep rate and thus maximum creep resistance. It is attributed to the higher volume fraction of Mg2Si, which can reduce grain boundary sliding during the creep test. Stress exponent of all the alloys is between 4.06 and 7.09 in the temperature range of 398 to 447 K. It is changed from the range of 3.96-4.89 to 8.62-12.62 under high-stress values at temperatures between 476 and 491 K. Creep activation energy under shear modulus-normalized stress of 0.010 and 0.012 is close to that of dislocation pipe diffusion of Mg. Under higher stress values at the high temperatures the creep activation energy is equal to that of Mg lattice diffusion. According to the obtained stress exponent values and creep activation energies, pipe-diffusion climb controlled dislocation creep is the dominant mechanism at temperatures between 398 and 447 K, which changes to power-law breakdown (PLB) under high-stress values at 476 and 491 K.
Materials Science and Engineering: A, 2011
The effects of calcium and rare earth elements (RE) on the microstructure and creep properties of... more The effects of calcium and rare earth elements (RE) on the microstructure and creep properties of as-cast and thixoformed AZ91 magnesium alloy have been investigated. It has been shown that the amount of β(Mg17Al12) intermetallic compound decreases by adding Ca and RE elements into AZ91 alloy and new Al11RE3 and Al2Ca intermetallic compounds form in the microstructure. The coarsening of
Journal of Alloys and Compounds, 2010
In the present study, the effects of rare earth (RE) elements on the microstructure and coarsenin... more In the present study, the effects of rare earth (RE) elements on the microstructure and coarsening kinetics of the solid globular particle in the semisolid slurry of AZ91 magnesium alloy have been studied at 570°C and 580°C. The results showed that the coarsening kinetics of the solid globular particles in semisolid slurry of AZ91 alloy satisfies the Ostwald ripening theory.
Metallic Materials, 2017
Impression creep behavior of as-cast Mg-xSi alloys (x = 0.5, 0.8, 1.2 wt.%) was studied under she... more Impression creep behavior of as-cast Mg-xSi alloys (x = 0.5, 0.8, 1.2 wt.%) was studied under shear modulus-normalized stress values ranging from 0.009 to 0.016 at temperatures between 398 and 491 K. The results show that creep properties of these alloys are improved with increasing Si content under all the applied loads and temperatures, and Mg-1.2Si alloy has minimum creep rate and thus maximum creep resistance. It is attributed to the higher volume fraction of Mg2Si, which can reduce grain boundary sliding during the creep test. Stress exponent of all the alloys is between 4.06 and 7.09 in the temperature range of 398 to 447 K. It is changed from the range of 3.96-4.89 to 8.62-12.62 under high-stress values at temperatures between 476 and 491 K. Creep activation energy under shear modulus-normalized stress of 0.010 and 0.012 is close to that of dislocation pipe diffusion of Mg. Under higher stress values at the high temperatures the creep activation energy is equal to that of Mg lattice diffusion. According to the obtained stress exponent values and creep activation energies, pipe-diffusion climb controlled dislocation creep is the dominant mechanism at temperatures between 398 and 447 K, which changes to power-law breakdown (PLB) under high-stress values at 476 and 491 K.
Materials Science and Engineering: A, 2011
The effects of calcium and rare earth elements (RE) on the microstructure and creep properties of... more The effects of calcium and rare earth elements (RE) on the microstructure and creep properties of as-cast and thixoformed AZ91 magnesium alloy have been investigated. It has been shown that the amount of β(Mg17Al12) intermetallic compound decreases by adding Ca and RE elements into AZ91 alloy and new Al11RE3 and Al2Ca intermetallic compounds form in the microstructure. The coarsening of
Journal of Alloys and Compounds, 2010
In the present study, the effects of rare earth (RE) elements on the microstructure and coarsenin... more In the present study, the effects of rare earth (RE) elements on the microstructure and coarsening kinetics of the solid globular particle in the semisolid slurry of AZ91 magnesium alloy have been studied at 570°C and 580°C. The results showed that the coarsening kinetics of the solid globular particles in semisolid slurry of AZ91 alloy satisfies the Ostwald ripening theory.