Question - What Is The Grain Size Of Lead As An Element And As An Alloy Such As Lead Tin Alloy?
Answer -
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 difficult since it is difficult to locate the grain boundaries; there is no segregation and composition distinction in the case of micro structural features in pure elements. However, in the case of alloys such as PbSn alloys, composition difference between the primary dendrites and the eutectic matrix allows for grain size measurement. As most of PbSn alloys exhibit a dendritic structure surrounded in a eutectic matrix, the dendrite arm spacing is used instead of grain size. For some alloy systems, there are relationships to correlate grain size to solidification rate.
In the case of pure Pb and PbSn alloy as well as most other alloys, primary dendrite arm spacing (at normal solidification rates like those applicable through sand and even die casting) is of order some microns and can be decreased to some nanometers by Rapid Solidification processes like melt spinning. The solidification rate in the case of such processes can reach 1,000,000,000 [0C/s]. These processes have the capability of producing "Amorphous" structures in the case of some special alloys where grain size becomes meaningless. For more information on lead alloys, you are advised to refer to the 2nd volume of ASM handbooks, which is on nonferrous alloys and contains a section devoted to lead alloys.