中文摘要：

采用扫描电镜（SEM）、透射电镜（TEM）、电子探针（EPMA）和高温力学试验机等手段,研究了不同时效温度（200-800℃）对Ni-20Cr-18W-1Mo高温合金的元素晶界偏聚和力学性能的影响。结果表明,硫、磷元素的晶界偏聚临界时间随时效温度升高而缩短;时效温度对元素在晶界和晶内的成分分布有显著的影响;实验合金的抗拉强度和延伸率随时效温度升高而降低。分析发现,硫、磷元素在晶界中的含量随时效温度升高而增大直至两者分别在650和400℃时达到峰值,是合金在200-600℃区间力学性能降低的重要原因。

英文摘要：

The influence of aging temperature（200 to 800 °C） on grain boundary segregations in a Ni-20Cr-18W-1Mo superalloy was investigated by scanning electronic microscope（SEM）, transmission electron microscopy（TEM）, electron microprobe analyzer（EMPA） and a mechanical testing machine. Results indicate that the grain boundary segregation critical time of sulfur and phosphorus decreases with increasing of the aging temperature. Increasing of the aging temperature has a conspicuous effect on the concentration distribution in the grain boundary and the grain core. Grain boundary concentrations of sulfur and phosphorus increase with raising the testing temperature until a peak value is obtained at 650 and 400 °C, respectively, which is the essential reason to the declined mechanical properties from 200 to 600 °C.