화학공학소재연구정보센터
Materials Science Forum, Vol.509, 69-74, 2006
The effect of hot rolling on room temperature ductility of a NiAl intermetallic compound
A Ni57Fe18Al25 alloy is produced by vacuum induction melting under an argon atmosphere and gravity cast into a copper chill mould. Ingots of 2 x 10 x 50 mm are re-heated at 1100 degrees C for 24 hours and hot rolled until a 25 % reduction is reached. Immediately, hot rolled plates are heat treated at 1100 degrees C for 1 hour and water cooled to room temperature. Microstructures of as cast, hot rolled and hot rolled plus heat treated specimens are characterized using scanning and transmission electron microscopy and x-ray diffraction. Specimens in the as-cast and hot rolled conditions show the presence of equiaxial and partially elongated beta-grains, respectively, with the presence of a thin gamma-phase decorating the grain boundaries. Hot rolled plus heat treated specimens have partially recrystallized beta-grains with 7-phase and (Ni,Fe)(3)Al at the grain boundaries. The hot rolled specimens have a room temperature ductility of approximately 5 % in tensile testing. This enhancement in ductility is attributed to the modification of the beta-grains by coexistence with a gamma-phase along the grain boundaries.