Degradation of High-temperature Oxidation Resistance for Ni-based Alloys by Re Addition and the Optimization of Re/Al Content

Md. Moniruzzaman, M. Maeda, Y. Murata, M. Morinaga
2003 ISIJ International  
High-temperature oxidation tests were conducted with two groups of Ni-based superalloys in order to elucidate the Re effect on oxidation resistance. One group of alloys was the Ni-8Cr-2Ti-10Al-Re system, characterized by 10 mol% Al content. The other group of alloys was the Ni-8Cr-2Ti-15Al-Re system, characterized by 15 mol% Al content. The alloy compositions were chosen with the aid of the d-electrons concept, so that any undesirable phases would not appear in the microstructure. Both cyclic
more » ... ture. Both cyclic and isothermal oxidation tests were carried out at 1 373 K for a total time of 720 ks. The oxidation resistance decreased clearly with increasing Re content in the 10-Al series alloys, but did not in the 15-Al series alloys. The alloys having a Re/Al ratio (mol%) up to 0.1 exhibited very small mass change by oxidation, so the Re/Al ratio was indeed a good indication for the design of superalloys having a good oxidation resistance. KEY WORDS: Ni-based superalloy; high-temperature oxidation resistance; Re effect. Fig. 3. SEM images and the corresponding characteristic X-ray images taken from the cross section of cyclically oxidized specimens; (a) A-1 and (b) A-9 alloy. Fig. 4. SEM images and the corresponding characteristic X-ray images taken from the surface of cyclically oxidized specimens; (a) A-1 and (b) A-9 alloy.
doi:10.2355/isijinternational.43.386 fatcat:tna4kqirvrgq3pxlo57ighxu74