No, Yugoslavia was not part of the USSR. While both Yugoslavia and the Soviet Union were socialist states, they had distinct political systems and histories.
Yugoslavia was formed after World War I and was unique in that it was a federation of several republics, including Slovenia, Croatia, and Serbia, among others. It pursued a path of non-alignment during the Cold War, often positioning itself in between the Western and Eastern blocs.
On the other hand, the USSR, or the Soviet Union, was a federation of multiple republics that were tightly controlled by the Communist Party and operated under a centralized government. While both countries had communist ideologies, Yugoslavia, particularly under the leadership of Josip Broz Tito, maintained its independence from Soviet influence and rejected Stalinist control.
In summary, while Yugoslavia and the USSR were both socialist countries, Yugoslavia was never a part of the Soviet Union.