A novel powder preparation technology using semi-solid rotational coaxial-cylinders

A novel powder preparation method, semi-solid powder preparation technology, has been developed, which consist of two processes, i.e., the formation of globular crystals from the melt using a semi-solid processing, and the separation of the globular crystals from the melt. An significant difference with the traditional powder preparation technology is that the powder prepared by this method is formed directly from the melt via a semi-solid process, which eliminates oxidation of the powder. Moreover, it is easy to self-form a low-melting-point alloy film on the powder surface, which avoids the use of an additional adhesive during the powder sintering process, and minimizes the contamination induced by the external additions, and improves the quality of sintered P/M parts. Experiments with a Sn-15wt.%Pb alloy show that this approach can generate high quality, single crystal powders without defects such as non-metallic inclusions, shrinkage, etc. Detailed results and analyses are presented and discussed.