Effect of production parameters on cooling rates of AA2014 alloy powders produced by water jet cooled, rotating disc atomisation

摘要

In this study, a novel type of rotating disc unit was designed and constructed and was used to produce rapidly solidified AA2014 alloy powders. Copper and stainless steel were used as the disc material and the temperature of the cooling water was selected as 0 deg C and 18 deg C. Effects of the production parameters, such as disc material, cooling water temperature, superheat of liquid metal and disc speed on the microstructure and the cooling rate of the powders, have been investigated. The microstructure of the produced powders was cellular and changed to cellular-dendritic with increasing powder size. It was found that cooling rates were relatively higher using a copper disc and 0 deg C cooling water temperature. The results indicated that cooling rates of 25 mu m powders produced with a copper disc were estimated as 1.01 X 10~6K s~(-1) and 9.02 X 10~5 K s~(-1) for 0 deg C and 18 deg C cooling water temperatures respectively. Decreasing the superheat of the liquid metal and increasing disc rotating speed also increased the cooling rates.