Isothermal hot compression tests were carried out on Mg-3.0Nd-0.2Zn-0.4Zr （mass fraction, %, NZ30K） alloy using a Gleeble-3500 thermo-simulation machine at temperatures ranging from 350 to 500 ℃and strain rates fro...
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Isothermal hot compression tests were carried out on Mg-3.0Nd-0.2Zn-0.4Zr （mass fraction, %, NZ30K） alloy using a Gleeble-3500 thermo-simulation machine at temperatures ranging from 350 to 500 ℃and strain rates from 0.001 to 1 s^-1. A correction of flow stress for deformation heating at a high strain rate was carried out. Based on the corrected data for deformation heating, a hyperbolic sine constitutive equation was established. The constants in the constitutive equation of the hyperbolic sine form were determined as a function of strain. The flow stresses predicted by the developed equation agree well with the experimental results, which confirms that the developed constitutive equations can be used to predict the flow stress of NZ30K alloy during hot deformation.
The primary phase evolution of ADC12 aluminum alloy rheo-processed by mechanical rotational barrel system was studied by differential scanning calorimetry（DSC）, optical microscopy（OM） and scanning electron microsc...
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The primary phase evolution of ADC12 aluminum alloy rheo-processed by mechanical rotational barrel system was studied by differential scanning calorimetry（DSC）, optical microscopy（OM） and scanning electron microscopy（SEM）. The semisolid slurry analyses show that the solid fraction of ADC12 aluminum alloy increases from 0.38 to 0.43 while the roundness decreases from 0.45 to 0.38 with increasing the rotational speed from 30 to 120 r/min. When the pouring temperature decreases from 620 to 580 °C, the primary α（Al） morphology changes from spheroidal to rosette-like. Besides, the average particle size of primary phase and solid fraction increase with the decrease of pouring temperature. By rheo-diecasting process, the components with fine, spherical and uniformly distributed primary α（Al） particles were obtained, and the best microstructure was contained at the pouring temperature ranging from 595 to 605 °C. The rheo-processing feasibility of ADC12 aluminum alloy can be explained by the grains controlled growth theory, and the semisolid slurry obeys the Mullins-Sekerka criterion when solidifying in the high pressure die casting machine.
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