A large proportion of cast aluminum alloys undergo dendritic structure formation during the solidification process. This dendritic solidification is a characteristic feature of many alloys, in which the liquid metal solidifies into tree-like, branched structures. These structures, called dendrites, play a central role in the properties of the resulting microstructure.
Various parameters are available to evaluate the quality of the solidified structure. One of these parameters is the degree of refinement of the eutectic, which describes how even and fine the eutectic structure is. Another important aspect for characterizing the structure is the so-called dendrite arm spacing. In particular, the distance between the secondary dendrite arms, i.e. the smaller branches of the main dendrites, provides information about the growth and solidification conditions of the alloy.
The VDG data sheet P220 defines a standardized method for measuring these secondary dendrite arms. These measurements serve as the basis for a detailed analysis of the solidification history of the material. The dendrite arm spacing provides valuable information about the cooling rate and thermal behavior during the solidification process. A smaller dendrite arm spacing usually indicates faster cooling, while larger spacing indicates slower solidification.
Using the measurement methods according to VDG Data Sheet P220, precise conclusions can be drawn about the solidification conditions and their influence on the microstructure and mechanical properties of the aluminum casting alloy.
Standard: VDG-Merkblatt P220
