A casing for a blisk of a turbomachine including an internal coating made of an abradable material, and a plurality of circumferential slots arranged in the coating of abradable material, the casing further including a circumferential cavity formed in the coating of abradable material, into which cavity the slots open, the slots opening into the cavity and extending between the cavity and an internal surface of the casing. A turbomachine can include such a casing and a blisk.