采用金相显微镜、扫描电镜、透射电镜及能谱分析等手段, 研究了磷含量对 GH761合金力学性能的影响. 结果表明: 磷含量低于0.040%时, 对合金室 温和650 ℃拉伸性能无明显影响. 适量磷显著延长合金的650 ℃, 637 MPa持久寿命, 最佳含量位于0.023%附近, 寿命高于970 h, 比磷含量为0.0007%时的寿命长3倍以 上. 磷含量升至0.040%时, 持久寿命又降至约220 h. 磷通过阻碍位错运动、促进晶 界析出、阻碍环境氧的沿晶侵入等机制, 提高GH761合金的持久寿命. 过高的磷含 量使晶界析出过量, 并导致η-Ni3Ti相析出, 弱化晶界, 降低合金的持久寿命.
When phosphorus content is below 0.040%, no obvious effect on the tensile properties of GH761 alloy at room temperature and 650℃ was observed. However, phosphorus influenced the stress rupture properties of GH761 alloy greatly. The peak value of the rupture life at 650 ℃ and 637 MPa appeared at 0.023% phosphorus. At the point, the life was longer than 970 h, more than 3 times of that when the phosphorus content is 0.0007%. Phosphorus can prolong the rupture life of GH761 alloy by inhibiting the dislocation glide, increasing the intergranular precipitation and blocking the diffusion of oxygen along gain boundaries. However, excessive addition of phosphorus lowered the grain boundary strength by deteriorating the grain boundary precipitation and causing the precipitation of η-Ni3Ti, which shortened the rupture life of GH761 alloy.
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