Fuyang Cao

Hot deformation behavior of spray formed Al-22Si-5Fe-3Cu-1Mg alloy

Abstract The hot deformation behavior of a spray formed Al-22Si-5Fe-3Cu-1Mg alloy was investigated by isothermal compression tests at temperature ranging from 350°C to 500°C and strain rate from 0.001 s−1 to 0.1 s−1. At the beginning of deformation, work hardening is the major factor. The flow stress quickly reaches a peak, followed by a continuous reduction, then a balance is established between the tendency to work harden and the tendency to flow soften. The stress curves appear almost in flat shape. A constitutive equation in the hyperbolic sine function for describing the deformation behavior was established and the hot deformation activation energy was determined to be 312.65 kJ/mol. It can be concluded that the temperature of extrusion should not be more than 500°C in order to avoid primary silicon coarsen.

A computational fluid dynamics (CFD) investigation of the flow field and the primary atomization of the close coupled atomizer

Abstract The gas flow fields of four atomizers were analyzed by both k – ɛ turbulence model and Reynolds stress turbulence model (RSM). The scattering angle of the main part of gas spray increased from 15.0° to 17.4° given by k – ɛ model and 17.2° to 19.0° given by RSM model, as the nozzle intersection angle increased from 5° to 65° at the operating gas pressure of 1.0xa0MPa, which also moved the merging position of the annular peak. There is a high pressure area downstream of the delivery tube which contributes to the sheet breakup. Comparing the simulation results with the experimental data, it is found that RSM model is more accurate than k – ɛ model and proved that computational fluid dynamics is an effective method to simulate the gas flow of the close coupled atomizer.