铸态Ni-Pt二元合金的显微组织及力学性能

Microstructure and Mechanical Properties of As-cast Ni-Pt Binary Alloys

通过光学显微金相分析、XRD分析以及显微硬度测试等实验手段，研究Pt添加量为5%-60%的铸态Ni-Pt二元合金的显微组织与力学性能。实验结果表明，Pt质量分数在5%-60%的Ni-Pt二元合金铸态组织为NiPt单相固溶体，且Ni-Pt固溶体为置换型固溶体，其固溶强化主要由Pt原子固溶到Ni基体中产生晶格畸变所导致，各晶面间距d随铂质量分数呈线性增大的趋势，显微硬度随Pt质量分数的增加而增大，且满足：Hv=2.10×Pt%＋85.04的线性数学表达式；铸态组织的柱状晶区的柱状晶随铂质量分数的增加向等轴晶和树枝晶发展，晶粒尺寸得到细化。当Pt质量分数达到6%时，铸态组织表现为发达的树枝晶，存在铸造裂纹。

The microstructure and mechanical properties of as-cast Ni-Pt binary alloys were studied by optical microscopy, X-ray diffraction（XRD） quantitative and qualitative analysis, micro-hardness testing. The results showed that Ni -Pt binary alloy is composed of NiPt single phase solid solution, the solid solution is substitutional solutes. Solid solution strengthening effect is caused by lattice distortion which induced by Pt atoms dissolve into Ni lattices. Each of interplanar spacing d is a linear increasing trend with the content of Pt. And also, the micro-hardness of the alloy increases when Pt content raises, which meets the following mathematical expressions：Hv=2.10×Pt%＋85.04. Columnar crystal of as-cast organization changes into isometric and dendrites with the increase of the content of platinum and the grain size is refined. When the mass fraction of Pt reaches 60%, the as-cast organization is characterized by plentiful dendrites, and there are the casting cracks.