Microstructural Evolution during Creep of Ni-Base Solid Solution Alloys and In-Situ Observation at High Temperature

摘要

Changes of creep curves and microstructure during creep were studied using Ni-18.5Cr and Ni-18.5Cr-16W alloys. Typical normal type creep curves were obtained at 700 and 800℃ for Ni-18.5Cr alloy. Oscillation of creep rates was observed at 900℃ for this alloy. On the other hand, tertiary creep dominant curves with an inverse transient were obtained at 700 to 900℃ for Ni-18.5Cr-16W alloy. Although subgrains formed significantly in Ni-18.5Cr alloy at 700℃, dislocations distributed uniformly without forming subgrains in Ni-18.5Cr-16W alloy at 700℃. According to in-situ observation during creep, voids often developed at new grain boundaries formed near grain boundaries in Ni-18.5Cr alloy.