(1. 遼寧工業(yè)大學(xué) 材料科學(xué)與工程學(xué)院，錦州 121001；
2. 中國科學(xué)院 金屬研究所，沈陽 110016)
摘 要: 采用SEM和TEM分析蠕變前、后的顯微組織，研究定向凝固N(yùn)iAl-Cr(Mo)-W/Nb合金在1 223~1 373 K溫度區(qū)間的拉伸蠕變行為的機(jī)理。結(jié)果表明：定向凝固N(yùn)iAl-Cr(Mo)-W/Nb合金的橫向顯微組織為典型的胞狀共晶，縱向顯微組織具有明顯的方向性，Cr(Mo)相以片層狀沿凝固方向分布。在所采用的溫度和外加應(yīng)力條件下，合金蠕變曲線均具有較短的減速蠕變階段和相當(dāng)長的穩(wěn)態(tài)蠕變階段及較高的蠕變應(yīng)變，蠕變應(yīng)變范圍為15%~28%。蠕變過程發(fā)生動(dòng)態(tài)回復(fù)和動(dòng)態(tài)再結(jié)晶，蠕變過程是由擴(kuò)散和位錯(cuò)蠕變共同控制。合金蠕變斷裂主要受蠕變裂紋的形成與擴(kuò)展的控制，蠕變斷裂的方式為沿相界的剝離。
關(guān)鍵字: NiAl基合金；定向凝固；蠕變；蠕變斷裂
NiAl-Cr(Mo)-W/Nb alloy
（1. School of Materials Science and Engineering, Liaoning University of Technology, Jinzhou 121001, China;
2. Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China）
Abstract:The microstructures before and after creep were also analyzed by SEM and TEM. The tensile creep behavior and mechanisms of directionally solidified (DS) NiAl-Cr(Mo)-W/Nb alloy were investigated in the temperature range of 1 223−1 373 K. The results show that the transverse microstructure of DS NiAl-Cr(Mo)-W/Nb alloy is typically eutectic cell of NiAl matrix and Cr(Mo) phase. The lamellar Cr(Mo) phase of the longitudinal microstructure is arranged along the direction of the directional solidification. At the present experiment, all of the creep curves of DS NiAl-Cr(Mo)-W/Nb alloy have the similar shape, i.e. shorter primary creep, longer steady state creep stage and higher creep strain. The creep strains are 15%−28%. The creep deformation mechanism is probably controlled by high temperature diffusion and dislocation creep. The creep fracture of this alloy is controlled by formation and propagation of the cracks at the phase boundaries, and the creep fracture mode is debonding along the phase boundary.
Key words: NiAl-based alloy; directional solidification; creep; creep rupture
