Aluminum blind rivets have aluminum sealed head with steel mandrel.

2) Aluminum open Head countersunk rivets:

Aluminum open head countersunk rivets have aluminum head with a steel mandrel. The rivet is countersunk to fit flush with surface that is being riveted

3) Aluminous flange head rivets:

Aluminum flange head rivets have an extra large aluminum head which spreads the load over a wider area. This pop rivet has a steel mandrel.