浇注温度对Ni-Cr-Co-Mo-Ti-Re-Hf-Al-W-Ta单晶高温合金组织和持久性能的影响

Influence of Pouring Temperature on Microstructures and Stress Rupture Properties of Ni-Cr-Co-Mo-Ti-Re-Hf-Al-W-Ta Crystal Superalloy

在定向真空凝固炉中,分别采用1560℃、1510℃两种不同的浇注温度制备Ni-Cr-Co-Mo-Ti-Re-Hf-Al-W-Ta单晶试棒,采用OM和SEM分析了不同浇注温度下合金的组织,测试了不同浇注温度下合金在1100℃/140 MPa条件下的持久性能,研究了浇注温度对Ni-Cr-Co-Mo-Ti-Re-Hf-Al-W-Ta合金组织和持久性能的影响。结果表明,浇注温度较低时,合金表面可见链状雀斑组织,枝晶间距和共晶增加且分布不均匀,元素偏析程度较大,γ′相尺寸稍大。浇注温度较低时,合金热处理后显微孔洞和残余共晶较多,γ′相尺寸和形态无明显变化,雀斑附近残余共晶稍多。浇注温度较低时,合金持久寿命较短,枝晶间距、残余共晶和显微孔洞的增加为合金持久寿命较短的主要原因。

The Ni-Cr-Co-Mo-Ti-Re-Hf-Al-W-Ta single crystal superalloy test bars were casted at at 1560℃and 1510℃in the directionally solidified furnace.The microstructures of the alloy with different pouring temperatures were analyzed by using of OM and SEM.The stress rupture properties of the alloy at 1100℃/140 MPa were tested.The influence of pouring temperature on the microstructures and stress rupture properties of the Ni-Cr-Co-Mo-Ti-Re-Hf-Al-W-Ta alloy was investigated.The results showed that with lower pouring temperature,the chain freckles formed on the surface of the alloy,the dendrite arm spacing andγ/γ′eutectic increased and have not evenly distributed,the extent of elements segregation was large,the size ofγ′phase was slightly large.The micropore and residual eutectic were large,the size and morphology of theγ′phase after heat treatment had no obvious change and there was much more residual eutectic around with freckles with lower pouring temperature.The stress rupture lives were low with lower pouring temperature,because the dendrite arm spacing,eutectic and micropore increased.