Grain size of lead-element alloy-tin alloy

Question

What is the grain size of lead as an element and as an alloy such as lead tin alloy?

Answer 1

Grain size in alloys and pure elements is a function of their solidification rate. The higher the solidification rate, the smaller the grains are. Determination of grain size in pure elements is rather hard because it is hard to locate the grain boundaries; there is no segregation and composition distinction in case of micro structural characteristics in pure elements. However, in the case of alloys such as Pb-Sn alloys, composition differentiation between the most important dendrites and eutectic matrix permits for grain size measurement. As most of Pb-Sn alloys exhibit a dendritic structure surrounded in eutectic matrix, the dendrite arm spacing is employed instead of grain size. For some alloy systems, there are relationships to associate grain size to solidification rate. In case of pure Pb and Pb-Sn alloy and most additional alloys, primary dendrite arm spacing (at a normal solidification rates like those applicable by sand and even die casting) is of order some microns and can be reduced to some nanometers by Rapid Solidification procedures like melt spinning. The solidification rate in case of such procedures can reach 1,000,000,000 [0C/s]. These processes have the capacity of producing ‘Amorphous’ structures in case of some special alloys where granule size becomes meaningless.