While conducting a pleasure flight the aircraft right rear landing wire failed. The pilot returned to TYABB and landed normally. The landing wire examination found that the wire failed in fatigue initiating from two subsurface defects in approximately the middle of the wire length. A sample taken some 40 mm from the fracture surface contained intermetallic stringers reducing the integrity of the material. Size of the stringers was consistent with the size of the subsurface defects. The analysis indentified the stringers to be an aluminium based intermetallic, possibly from the refractory material used in production of the material. The material composition and microstructure was typical of a drawn and rolled 316 stainless steel. The manufacturer advised the wire was made of 316S16 steel.