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TiAl金属间化合物和713 LC、738 LC镍基高温合金的抗氧化性能，同时提高应力集中部位的低周疲劳裂纹萌生寿命和蠕变裂纹萌生时间等力学性能，采用NiCrAlY电极对TiAl金属间化合物和713 LC、738 LC镍基高温合金进行放电表面改性。进行了氧化试验、高温低周疲劳试验和蠕变试验。改性后的TiAl表面出现大量的微裂纹，导致改性试验中断。采用该技术可显著提高713 LC和738 LC在900-1000 ℃范围内的抗氧化性能。738 LC缺口紧凑拉伸试样在800 ℃下的低周疲劳裂纹萌生寿命与未处理试样相当。CT试样在900 ℃下的蠕变裂纹萌生时间得到改善，氧化程度降低，而未处理试样的氧化膜剥落较多。

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.