NiAl基定向共晶合金的组织和压缩性能

Microstructure and Compressive Properties of DS NiAl-based Eutectic Alloy

采用具有高温度梯度的液态金属冷却工艺,制备Ni-33Al-28Cr-5.94Mo-0.05Hf-0.01Ho共晶合金。利用扫描电镜(SEM)和电子探针(EPMA)分析该合金的微观组织,用Gleeble1500测试合金室温压缩性能。研究表明:该工艺能够制备出较规则的定向组织;并细化NiAl/Cr(Mo)共晶层片,使NiAl/Cr(Mo)两相发生固溶度扩展,产生了有效的固溶及第二相强化;合金的室温压缩性能随抽拉速率的增加变化较小。

The microstructure and mechanical properties of an eutectic Ni-33Al-28Cr-5.94Mo-0.05 Hf-0.01Ho alloy fabricated by directional solidification under two withdrawal rates （3 and 8 mm/min） are presented. It is shown that a promising as-cast microstructure is formed under the higher withdrawal rate, which can be characterized by the refinement of eutectic lamellae between the NiAI and Or （Mo） phases within the cells. The amount of alloying elements in NiAI and Cr （Mo） phases increased, which led to effective solid solution and second phase strengthening. As a positive response to this, superior room temperature mechanical properties with yield strength of 950 MPa and compressive strain of 25 % are obtained. The compressive properties at room temperature strength did not vary at the different withdrawal rates. Based on these investigations, the mechanism responsible is discussed.