The magnification is 100X, but the etchant was not recorded. The alpha (the only phase in the specimen except for impurity inclusions) is cored. Note that each alpha grain is a singe dendrite. There are shrinkage pores as well.
The copper has lost its characteristic pink or yellow color because of the nickel.
This alloy is used as a "non-tarnishing" substitute for silver in drafting instruments, etc.
It does tarnish; and it doesn't look like silver !