No abstract

The surface layer of the samples of Al4.5 %Cu1.0% Si alloy was developed by CO 2 laser using TiC and WC particles. Because the oxide film on the surface it was impossible to introduce the TiC particles into the melt, as the WC particles could broken the oxide film and could penetrate to the melt. The microstructure of resolidified layers were cellular or dendritic with cast texture. The bands were overlaped and so the resolidified structure was partly heat treated. The carbide particles reacted with the melt.

The different solidification processes occuring in steels can be well studied by using the microstructure investigation. The microstructure can be observed after the sample preparation by using a special type of Oberhoffer etching. The changes in the cooling rate can be described by determining the secondary dendrite arm spacing. A relative cooling rate can be calculated by applying the relationship between the secondary dendrite arm spacing and the cooling rate which characterises the changes of cooling conditions in the ingot during the solidification..

No abstract