快速凝固对DZ98M成分合金微观组织的影响

Influences on Microstructure of DZ98M Composition of the Alloy by Rapid Solidification

摘要:

本文采用激光增材制造技术(LEN98M)和传统定向凝固技术(DZ98M)制备镍基高温合金,通过OM,SEM,EDS,XRD,EPMA,DTA等方法分析比较合金的枝晶形态、微观组织、凝固特征温度、元素偏析情况。结果表明,LEN98M合金的一次枝晶间距约为70μm,仅为传统铸造合金DZ98M的1/5,二次枝晶不发达。在枝晶尺度范围内LEN98M合金存在更加明显的偏析行为,γ?相尺寸大且形态不规则,无碳化物析出,枝晶间共晶为尺寸小更加分散的γ?块状。

Abstract:

In this paper a Ni-based superalloyalloy was fabricated by laser additive manufacturing technology(LEN98M) and by trainditional directional solidification (DZ98M), respectively. The solidification morphology, microstructures, elements segregation are systematically investigated by using optical microscope(OM), scanning electron microscope(SEM), energy dispersive spectroscopy(EDS), X-ray diffraction(XRD), electron microprobe(EPMA), differential thermal analysis(DTA). The results show that the primary dendrite arm spacing of the LEN98M alloy is 70 μm and reduced as 1/5 of the DZ98M alloy. There is a serious segregation of alloying elements in the range of dendrite scale. The morphology of γ? phase are irregular and no precipitation of carbides observed in as-casted LEN98M alloy. There are smaller γ/γ? eutectic dispersed in interdendritic regions.