The change of the skull shape and size has been predicated through computer simulation technique and compared with the experimental results. The microstructure of the skull and the elemental line distribution in the s...The change of the skull shape and size has been predicated through computer simulation technique and compared with the experimental results. The microstructure of the skull and the elemental line distribution in the skull have been analyzed with optical microscope and EPMA etc. The results show that the skull height and thickness become small with increasing melting power; the skull consists of two zones, that is, fine equiaxial crystal zone and coarse columnar crystal zone; there exists some segregation in the bottom of the skull.展开更多
The effect of Ru addition on solidification behavior, microstructure and hardness of Re-free Ni-based equiaxed superalloys with high Cr content has been investigated. With the increase of Ru, the solidus temperature o...The effect of Ru addition on solidification behavior, microstructure and hardness of Re-free Ni-based equiaxed superalloys with high Cr content has been investigated. With the increase of Ru, the solidus temperature of the alloys and the γ＂ solvus temperature decreased, respectively. However, the liquidus temperatures of the alloys bad no obvious change. The microstructure of the as-cast alloys was mainly composed of γ, γ＇, γ＇/γ＇ eutectic and MC carbides. The γ/γ＇ eutectic was completely dissolved after the heat treatment. The morphology of γ＇ was more cuboidal in heat-treated alloys with increasing Ru. Furthermore, the volume fraction of γ＇ in the as-cast and heat-treated alloys diminished upon the increase of Ru. It was noted that Ru addition changed the segregation behaviors of Cr and Mo in the alloys from positive segregation element to negative segregation element and promotes the segregation degree of W. As the Ru content increased, the magnitude of segregation of the positive segregation elements Ta and Ti increased accordingly. Meanwhile, the magnitude of Al segregation decreased and Ru tended to segregate in the dendrite core. In addition, the hardness of the alloys improved and their porosity reduced with increasing amount of Ru.展开更多
文摘The change of the skull shape and size has been predicated through computer simulation technique and compared with the experimental results. The microstructure of the skull and the elemental line distribution in the skull have been analyzed with optical microscope and EPMA etc. The results show that the skull height and thickness become small with increasing melting power; the skull consists of two zones, that is, fine equiaxial crystal zone and coarse columnar crystal zone; there exists some segregation in the bottom of the skull.
文摘The effect of Ru addition on solidification behavior, microstructure and hardness of Re-free Ni-based equiaxed superalloys with high Cr content has been investigated. With the increase of Ru, the solidus temperature of the alloys and the γ＂ solvus temperature decreased, respectively. However, the liquidus temperatures of the alloys bad no obvious change. The microstructure of the as-cast alloys was mainly composed of γ, γ＇, γ＇/γ＇ eutectic and MC carbides. The γ/γ＇ eutectic was completely dissolved after the heat treatment. The morphology of γ＇ was more cuboidal in heat-treated alloys with increasing Ru. Furthermore, the volume fraction of γ＇ in the as-cast and heat-treated alloys diminished upon the increase of Ru. It was noted that Ru addition changed the segregation behaviors of Cr and Mo in the alloys from positive segregation element to negative segregation element and promotes the segregation degree of W. As the Ru content increased, the magnitude of segregation of the positive segregation elements Ta and Ti increased accordingly. Meanwhile, the magnitude of Al segregation decreased and Ru tended to segregate in the dendrite core. In addition, the hardness of the alloys improved and their porosity reduced with increasing amount of Ru.
