INTEGRALLY DIRECTIONALLY SOLIDIFIED MICROSTRUCTURE OF AN NIOBIUM SILICIDE BASED ULTRAHIGH TEMPERATURE ALLOY
Integrally directional solidification of an advanced Nb silicide based ultrahigh temperature alloy was conducted with the use of special ceramic crucibles. The melt temperature was 2000℃ and the withdrawing rate was respectively 5, 10, 15, 30, 50, 80 and 100 μm/s. The directionally solidified microstructure was composed of primary (Nb,X)5Si3 rods and (Nb,Ti)ss + (Nb,X)5Si3 eutectic colonies (here X represents Ti and Hf elements) that distributed evenly and aligned erectly along the growth direction. The quenched solid/liquid (S/L) interfaces had the morphology of a series of protruded parallel eutectic cells along the growth direction. (Nb,Ti)ss and (Nb,X)5Si3 slices grew in a coupled manner in each eutectic cell, forming a typical lamellar eutectic morphology. Both the average diameter of eutectic cells and lamellar spacing in them decreased with the increase of withdrawing rates. The solidification path was that primary (Nb,X)5Si3 rods formed firstly and then the retained liquid around solidified into (Nb,Ti)ss + (Nb,X)5Si3 eutectic cells.
Nb silicide based alloy integrally directional solidification eutectic S/L interface
XIPING GUO HAISHENG GUO CHENGFANG YAO PING GUAN
State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Youyixi Ro School of Natural and Applied Science, Northwestern Polytechnical University, Youyixi Road 127, Xia
国际会议
第五届先进材料与加工国际会议(Fifth International Conference on Advanced Materials and Processing ICAMP-5)
哈尔滨
英文
1093-1098
2008-09-03（万方平台首次上网日期，不代表论文的发表时间）