摘要
Solidification behaviors of Pt-containing 718Plus superalloys were studied by scanning electron microscopy(SEM),energy dispersive spectrum(EDS),differential scanning calorimetry(DSC)and simulation calculations.It is found that Pt increases solidification range and decreases solidus temperature of the alloy and precipitation temperature of Laves+ γ eutectic phase since Pt enlarges the region of γ phase by increasing Nb solubility.In addition,Pt segregates to the interdendritic region and increases the segregation of Nb and Ti in the interdendritic region due to the strong attractive interactions between Pt and Nb/Ti.As a result,Pt promotes the precipitation of the Laves+ γ eutectic phase andηphase around eutectic phase.The increase of solidification range and segregation degrees of Nb and Al caused by Pt also promotes the precipitation and growth of γ'+γ" phase around eutectic phase.These results provide experimental bases for understanding the mechanism of Pt in solidification behavior of superalloys.
采用扫描电子显微镜(SEM)、能谱仪(EDS)、差示扫描量热法(DSC)和模拟计算研究含Pt高温合金718Plus的凝固行为。结果表明:Pt的添加通过增加Nb的溶解度、扩大γ相区范围来降低合金的固相线温度和Laves+γ共晶相的析出温度,从而增大凝固范围。Pt偏析于枝晶间区域,Pt与Nb/Ti间强吸引的相互作用使枝晶间Nb和Ti的偏析增加,因此促进Laves+γ共晶相及其周围η相的析出。Pt添加导致的凝固范围增大、Nb和Al的偏析程度的增加促进共晶相附近γ'+γ"相的析出和长大。这些结果为理解Pt在高温合金凝固行为中的作用机理提供了实验依据。
基金
The authors are grateful for the financial supports from the National Natural Science Foundation of China(Nos.51771018,51871022)
the Fundamental Research Funds for the Central Universities(Nos.FRF-GF-19-004B,FRF-GF-20-01A)。
