激光铸造Ni_(75)Al_(25-x)Si_x多相金属间化合物

Ni_(75)Al_(25-x)Si_x multi-phase intermetallic alloys by means of laser casting

利用激光铸造技术成功制备以原子百分比配置的Ni75Al25-xSix(x=0,20)多相金属间化合物合金.使用X射线衍射(XRD)、光学显微镜和扫描电子显微镜(SEM)对合金进行物相鉴定及显微组织分析.使用显微硬度计对其进行显微硬度测试.结果表明,未添加Si元素的合金主要由Ni3Al、γ-Ni和少量的NiAl相组成.显微组织呈细小、均匀的树枝晶,在枝晶间分布有层片状组织.添加原子分数20%的Si元素的合金,除了Ni3Al和-γNi外,还包括Al3Ni2和较多的NiAl相;显微组织呈均匀、致密的网状树枝晶生长;平均显微硬度742 HV,约为未添加Si元素合金的1.9倍.

The Ni75Al25-xSix （x=0, 20） multi-phase intermetallic alloys composed with atomic percentage were successfully fabricated with laser casting. Phase identification, microstructure observation and microhardness measurement of the alloys were analyzed with X-ray diffraction （XRD）, optical microscopy （OM）, scanning electron microscopy （SEM） and microhardness tester, respectively. The results showed that the alloy without addition of Si element contained only Ni3A1, γ-Ni solid solution and a few NiA1 phase. However, the alloy with addition of Si element consisted of Ni3A1, NiA1, A13Niz and γ-Ni solid solution. Microstructure changed from uniform and typical dendrite to netty dendrite. Microhardness of the alloy with addition of Si element was higher than that of the alloy without addition of Si element.