Study on improvement of high temperature strength in oxidation environment of intermetallic compound and Nickel-base superalloys by electric-discharge anti-oxidation surface treatment

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To improve both oxidation resistance and mechanical properties such as low cycle fatigue crack initiation life and creep crack initiation time of stress concentration part, electric-discharge surface modification technique was used, by which intermetallic compound TiAl and Nickel-base superalloys 713LC and 738LC were electric-discharged using NiCrAlY electrode. Oxidation test, high temperature low cycle fatigue test and creep test were carried out. The modified surface of TiAl have many microcracks and the the surface-modification test was interruptted. Oxidation resistance of 713LC and 738LC in ranged 900-1000ﾟC was improved significantly by this technique. Low cycle fatigue crack initiation life at 800ﾟC of 738LC notched compact tension specimen was comparable with non-treated one. Creep crack initiation time at 900ﾟC of the CT specimen was improved with less oxidation, while the oxide film of the non-treated one spalled much.