镍基单晶高温合金不同温度下的拉伸性能

为了研究一种镍基单晶高温合金从室温到1100℃范围的拉伸变形与断裂行为，利用扫描电子显微镜和透射电子显微镜对拉伸断口及变形后位错组态进行观察和分析.结果表明：合金的屈服和抗拉强度均在约800℃时达到峰值，而塑性与强度的变化规律基本相反.室温和中温拉伸条件下，断口表现为解理断裂；而高温时则为微孔聚集型断裂.室温拉伸条件下，合金的主要变形方式为单根位错剪切γ′相；高温下为位错绕过γ′相；中温下则表现为由剪切到绕过的过渡.

Tensile properties of a single crystal Ni-based superalloy at different temperatures

In order to investigate the tensile deformation and fracture behaviors of a single crystal Ni based superalloy in the temperature range from room temperature to 1100℃，the fracture surface and dislocation configuration after tensile deformation were characterized by scanning electron microscope and transmission electron microscope, respectively. The results reveal that the yield strength and ultimate tensile strength reach the peak value at 800℃，but the plasticity shows a contrary trend compared with the strength. At room and moderate temperature, the fracture mode is cleavage fracture, and changes to microvoid coalescence fracture at high temperature. The main deformation mechanism at room temperature is dislocation shearing γ′ phase, transits from shearing to by passing γ′ phase at moderate temperature, and changes to dislocation by passing γ′ phase at high temperature.