How to identify primary aluminium dendrites in Al-17Si alloy castings

[pukb]

Hello,

I am working on Al-17Si alloys. I have done some castings and in micro-structure I saw formation of Aluminium dendrites. I am unable to find out whether it is primary Al or eutectic Al. One way to find that is to find out Percentage of Si in the dendrites. But how do I do that?
Is there any other way to differentiate? Thanks in advance for any suggestions.

 

[chemisttree]

Put it into the electron microscope that can do EDX. Look at the Xrays.

 

[pukb]

Thank you it was really useful
looking to do edx at iisc