Behavior of Zr-rich phase in a cast NiAl-33.5Cr-0.5Zr alloy during heat treatment

There are many Zr particles in as-cast NiAl-33.5Cr-0.5Zr (at. pct) alloy, w hich usually exist at the edge of eutectic of beta -NiAl and cx-Cr. After a ir 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 a lloys and Ni2AlZr phase forms in the air cooling (A.C.) state alloys. Durin g solution treatment at 1450 degreesC, bulk and "fish bone" shape Zr-rich p hases form respectively in F.C. and A.C. state alloys. A 'river' shape Ni2A lZr phase forms after 1450 C for 1h F.C. and 850 degreesC for 12 h, F.C.. T he alloy has less pure Zr and Ni2AlZr phase after 1400 degreesC with both a ir and furnace cooling followed by 850 C and 950 C for 12 h, F.C. aging tre atments, 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 -N iAl and alpha -Cr in the alloy treated at 1400 degreesC, 2 h, F.C. and 950 degreesC, 12 h, F.C.