Eutectic and hypereutectic AlSi foundry alloys are increasingly being used in the casting of parts for the automotive and machinery industries. Such parts must have a fine homogenous silicon structure. In order to achieve this, the maker of the alloy or the foundryman adds Phosphorus to his melt. Aluminium phosphides are thus formed, being the nuclei of a fine granular silicon crystal growth. Unlike all other products Phosphorus releasing, with which Aluminium phosphide nuclei (AlP) get formed in a long time and under influence of furnace temperature, AlCuP Phosphorus rod already contains such nuclei, necessary for primary silicon grain refining. Besides, in case of use of an alloy of only Copper Phosphorus (CuP), it’s evident that the transformation of CuP in AlP happens in a not co-ordinated way and, consequently, the Phosphorus yield varies frequently both on primary silicon dimension and distribution. Vice versa, since AlCuP has been used and approved by foundrymen for years, it’s well-known that only 40 ppm P (AlP) are necessary to achieve an excellent grain refining.
Compared with other products phosphorus releasing (as CuP), AlCuP has the following advantages: