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

为了提高应力集中部位的抗氧化性和低周疲劳裂纹萌生寿命、蠕变裂纹萌生时间等力学性能，采用电火花表面改性技术，对金属间化合物TiAl和镍基高温合金713LC和738LC进行NiCrAlY电极放电处理。进行了氧化试验、高温低周疲劳试验和蠕变试验。TiAl表面有许多微裂纹，表面改性试验中断。该技术显著提高了713LC和738LC在900-1000ﾟC温度范围内的抗氧化性。738LC缺口紧凑拉伸试件在800ﾟC下的低周疲劳裂纹萌生寿命与未处理试件相当。随着氧化程度的降低，CT试件在900ﾟC的蠕变裂纹萌生时间延长，而未处理的试件氧化膜剥落较多。

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.