Microstructure and room temperature mechanical properties of NiAl-Cr(Mo)-(Hf, Dy) hypoeutectic alloy prepared by injection casting
(1. Shenzhen Institute, Peking University, Shenzhen 518057, China;
2. College of Engineering, Peking University, Beijing 100871, China;
3. Shenzhen Airline, Shenzhen Bao’an International Airport, Shenzhen 518128, China;
4. Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China)
2. College of Engineering, Peking University, Beijing 100871, China;
3. Shenzhen Airline, Shenzhen Bao’an International Airport, Shenzhen 518128, China;
4. Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China)
Abstract: The NiAl-Cr(Mo)-(Hf,Dy) hypoeutectic alloys were prepared by conventional casting and injection casting techniques respectively, and their microstructure and room temperature mechanical properties were investigated. The results reveal that with the addition of Hf and Dy, the Ni2AlHf Heusler phase and Ni5Dy phase form along the NiAl/Cr(Mo) phase boundaries in intercellular region. By the injection casting method, some Ni2AlHf Heusler phase and Ni5Dy phase transform into Hf and Dy solid solutions, respectively. Moreover, the microstructure of the alloy gets good optimization, which can be characterized by the fine interlamellar spacing, high proportion of eutectic cell area and homogeneously distributed fine Ni2AlHf, Ni5Dy, Hf solid solution and Dy solid solutions. Compared with conventional-cast alloy, the room temperature mechanical properties of injection-cast alloy are improved obviously.
Key words: NiAl based hypoeutectic alloy; Hf; Dy; injection casting; microstructure; mechanical properties