There are many Zr particles in as-cast NiAl-33.5Cr-0.5Zr (at. pct) alloy, which usually exist at the edge of eutectic of beta -NiAl and cx-Cr. After air and furnace cooling solution treatments, far 1400 degreesC, 2 h and 1450 degreesC, 1 h, pure Zr phase remains in the furnace cooling (F.C.) state alloys and Ni2AlZr phase forms in the air cooling (A.C.) state alloys. During solution treatment at 1450 degreesC, bulk and 'fish bone' shape Zr-rich phases form respectively in F.C. and A.C. state alloys. A 'river' shape Ni2AlZr phase forms after 1450 C for 1h F.C. and 850 degreesC for 12 h, F.C.. The alloy has less pure Zr and Ni2AlZr phase after 1400 degreesC with both air and furnace cooling followed by 850 C and 950 C for 12 h, F.C. aging treatments, respectively. Additionally, there is a ternary eutectic of NiAlZr and a phase enriched Zr and Cr forms at the edge of the eutectic of beta -NiAl and alpha -Cr in the alloy treated at 1400 degreesC, 2 h, F.C. and 950 degreesC, 12 h, F.C.
Hui LI, sJianting GUQ, Wanhui LAI and Shuhe WANG Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China
The microstructure and creep behavior of a DS NiAI-Fe(Nb) multiphase intermetallic alloy have been investigated. This alloyexhibits dendritic structure, in which dendritic arm is β-(Ni,Fe)(Fe,Al) phase surrounded by interdendritic region of γ'/γ phase.The results of the creep test indicated that all of the creep curves have similar characteristic, which is a short primary creepstage and a dominant steady state creep stage, and the creep strain ranges from 18% to 52%. The apparent stress exponentand the apparent activation energy were analyzed and discussed. The mechanism of the creep deformation was also analyzedby the observation of TEM.
Yihui QI, Jianting GUO and Chuanyong GUIDepartment of Superalloys, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China
