喷铸工艺制备NiAl-Cr(Mo)-(Hf,Dy)亚共晶合金的组织及室温力学性能(英文)

Abstract

采用普通重力铸造和喷铸制备NiAl-Cr(Mo)-(Hf,Dy)亚共晶合金,研究两种工艺制备的合金的微观组织和室温力学性能。结果表明,Hf和Dy元素的添加导致Ni_2AlHf Heusler相和Ni_5Dy相在NiAl/Cr(Mo)相界面析出。喷铸工艺促使部分Ni_2AlHf Heusler和Ni_5Dy相分别转变为Hf固溶体和Dy固溶体相,层片间距得到细化,共晶胞的面积比以及均匀分布的Ni_2AlHf、Ni_5Dy、Hf固溶体和Dy固溶体相增加。对比普通铸造合金,喷铸合金的室温性能得到明显提高。

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.