Cooling Rate Calculation of Non-Equilibrium Aluminum Alloy Powders Prepared by Gas Atomization

Artikel i vetenskaplig tidskrift, 2009

The cooling rate of aluminum alloy powders prepared by ultrasonic gas atomization process was calculated through the convection heat transfer principle. A simple and theoretical model is established, which can be expressed as vertical bar dT(d)/dt vertical bar =12/rho.C(p) . (T(d) - T(f)) . k(g)/d(2). The average cooling rates of Al-Ni-Ce-Fe-Cu alloy powders prepared by argon gas atomization and by helium gas atomization are about 10(4)similar to 10(7) K/s and 10(5)similar to 10(8) K/s, respectively. The critical cooling rate is calculated to be 3.74 x 10(5) K/s for Al-Ni-Ce-Fe-Cu alloy amorphous powders prepared by argon gas atomization. The cooling rates of gas-atomized powder particles estimated from secondary dendrite arm spacing are in consistence to those predicted from the theoretical model.