中文摘要：

主要论述水冷铜坩埚内的Czochralski定向凝固、电子束定向凝固、光悬浮定向凝固、整体定向凝固和电磁冷坩埚定向凝固5种定向凝固的基本原理,优缺点以及研究定向凝固Nb-Si基超高温合金所取得的进展.现阶段,基本不用Czochralski定向凝固和电子束定向凝固研究Nb-Si基超高温合金了;到目前为止,光悬浮定向凝固是制备研究Nb-Si基超高温合金的主要手段;整体定向凝固制备的Nb-Si基超高温合金的断裂韧性已达20 MPa·m1/2左右;电磁冷坩埚定向凝固制备的Nb-Si基超高温合金的高温拉伸强度已达200 MPa （1250℃）.

英文摘要：

The fundamental principles,advantages and disadvantages of Czochralski directional solidification （C-DS） in a copper crucible,electron beam directional solidification （EBDS）,optical floating zone melting （OFZ）,integrally directional solidification （IDS） and electromagnetic cold crucible directional solidification （ECCDS） and the progress of directionally solidified Nb-Si based superalloys are mainly discussed.Presently,C-DS and EBDS are not used to research Nb-Si based superalloys; heretofore,OFZ is the main body of researching Nb-Si based superalloys;the fracture toughness of Nb-Si based superalloys is increased to approximate 20 MPa · m1/2 by IDS; the high temperature tensile strength is improved to 200 MPa （1250 ℃） by ECCDS.