定向凝固NiAl-Cr(Mo)-Hf(Ho)共晶合金的组织与性能

来源期刊：金属学报2010年第6期

论文作者：肖璇 谢亿 郭建亭

文章页码：701 - 707

关键词：NiAl合金； 定向凝固工艺； 显微组织； 力学性能

Key words：NiAl alloy； directional solidification； microstructure； mechanical property

摘    要：通过液态金属冷却技术制备了名义成分为Ni-30.4Al-34Cr-4.3Mo-0.1Hf-0.05Ho(原子分数,%)的定向合金.定向凝固工艺消除了普通铸造合金中的初生Cr(Mo)相,获得了共晶组织.随抽拉速率从8 mm/min提高到15 mm/min,合金中的共晶胞尺寸从115μm减小到85μm,共晶胞间距变窄,胞间混乱区减少.与普通铸造相比,定向凝固工艺能提高该共晶合金的室温、高温拉伸强度,高温拉伸塑性以及室温断裂韧度,并且定向合金的上述力学性能随抽拉速率增大而增大.

Abstract: The alloy with nominal composition of Ni-30.4Al-34Cr-4.3Mo-0.1Hf-0.05Ho(atomic fraction,%) has been directionally solidified at two withdrawal rates by liquid metal (Sn) cooling (LMC) process.Compared to the as-cast alloy,directional solidification process eliminates primary Cr(Mo) phase.With increasing withdrawal rate from 8 to 15 mm/min,the diameter of NiAl/Cr(Mo) eutectic cell decreases from 115 to 85μm.In addition,the intercellular spaces and disordered regions become less.In virtue of the disappearance of primary Cr(Mo) phase,the mechanical properties of directionally solidified alloys are better than those of as-cast alloy and are further improved with increasing withdrawal rate.