Posted by Wen Yang on December 01, 2009 at 22:59:22:
A major impediment of understanding the initial solidification is the difficulty of observing the shape and size of sub-surface hooks in cast samples.Special etching reagents are required to reveal clearly the initially solidified structure near the hook,prior to subsequent phase transformations.
Although picric acid solution reveals the dendritic structure,the hook is difficult to distinguish from the rest of the microstructure.Oberhoffer's reagent relies on the segrefation of phosphorus,and can only reveal the linear profile of a hook but not the dendritic structure close to it.Thus, can anyone suggest a better etching reagent? Thanks!
And can you send the information to my email:yangwen-flying@163.com
Appreciate!