alias may not come over in a join or relate in the way you want see this comment
If you do not want your fields to be prefixed with the table name after a join, open the attribute table, click the Table Options menu, then uncheck Show Field Aliases.
Indentify tool in 10.5
Customizing field properties and their display Identify uses the column properties that you manage in the Table window in ArcMap. For example, you can specify alias names for fields that will be used instead of the often-cryptic DBMS field names, or you can hide the display of some columns. This setting also hides their display in the identify results.
consult your versions help to see if it didn't at some stage