A turbine nozzle for a turbomachine, including inner and outer annular platforms connected together by vanes, the inner platform carrying annular elements of abradable material co-operating with annular wipers of a rotor of the turbomachine to form a labyrinth seal, these elements of abradable material being carried by annular sheet-metal sectors of substantially L-, S-, or C-shaped section that are fastened by brazing or welding at their outer peripheries to the inner platform and at their inner peripheries to the elements of abradable material.