Andrei, from what I can tell, the T-64/A turret was cast with cavities in the cheeks to add aluminium alloy later, but what was done to cast the T-72A turret? I heard here on Tank-Net once that the filler was poured in through small holes on top of the cheeks, but that never made sense to me because some casting material like casting sand/moulding sand must be used to form the cavity, and then it must be removed before the filler is poured in. Since the cavities are fully enclosed, it seems difficult or almost impossible to get the casting material out of the cavities except through those small holes, so the casting material must also be the filler.
I'm just thinking aloud, really, so please correct me if I'm wrong.
According to Zaloga's book a number of solutions were tried. Steel with aluminum filler, steel with aluminum filler with corundum spheres, corundum filler, and I have seen reference to spaced arrays of high hardness steel also. The turret armor composition does not necessarily correspond with which model of T-64 it is either; the composition changed during production, and some were also retrofitted with newer armor fill.
The T-64 program was basically a mess, though for a brief time it was indisputably the most advanced tank in the world.
Useful info, thanks, but I am specifically referring to the common "Kvartz" turret.