Yes, the microstructure of the same material can show variations in grain size after being etched with two distinct etchants.
The grain size of a material is a function of various factors such as the processing history, heat treatment, and the chemical environment. When a material is etched with a particular etchant, the chemical reaction between the etchant and the material's surface can alter the surface topography and reveal the microstructure of the material.
Different etchants have different chemical compositions, and they react differently with the material's surface. As a result, different etchants can reveal different features of the material's microstructure, including the grain size.
For example, some etchants preferentially attack the grain boundaries, while others attack the grains themselves. If two different etchants are used, one that attacks the grain boundaries and another that attacks the grains themselves, the resulting microstructures may look different, with variations in the grain size.
Therefore, it is possible for the microstructure of the same material to show variations in grain size after being etched with two distinct etchants.