Hq. Zhu et al., THE EFFECT OF SILICON ON THE MICROSTRUCTURE AND SEGREGATION OF DIRECTIONALLY SOLIDIFIED IN738 SUPERALLOY, Materials at high temperatures, 12(4), 1994, pp. 285-291
The effect of silicon on the microstructure and solidification segrega
tion of directionally solidified IN738 nickel-based superalloy was stu
died. Directional solidification at various solidification rates and p
artial directional solidification plus rapid quenching were applied. M
etallographic analysis and an electron microprobe were mainly used to
observe and measure the microstructure and elemental segregation of th
e alloy, respectively. It was found that silicon affected the morpholo
gy of the liquid-solid interface of the alloy during solidification an
d gave the alloy a tendency to form well-developed dendrites. The addi
tion of silicon enlarged the solidus-liquidus temperature interval, an
d the solidification rate also greatly influenced the interval. The in
terval increased with increasing solidification rate. Silicon promoted
the precipitation of the gamma/gamma' eutectic, and also affected its
precipitation temperature. Silicon segregated mainly in interdendriti
c regions, and promoted the segregation of other elements. All of the
effects of silicon on the alloy related to the solidification rate.