小角度晶界对单晶高温合金N5持久性能的影响

Effect of Low Angle Grain Boundaries on Rupture Properties of Single Crystal Superalloy N5

以二代N5单晶高温合金为研究对象,利用高速凝固法(HRS)技术通过籽晶法制备了分别含有5.4°、9.8°、15.8°、18.4°小角晶界的N5合金双晶板。对含不同小角度晶界的N5合金双晶板所制备的标准样品在870℃下进行高温拉伸性能测试,在750℃/820 MPa和1093℃/158 MPa条件下进行横向持久性能测试,再借助扫描电镜对各断口形貌进行分析。结果表明:随着小角晶界取向差的增大,N5合金的拉伸性能逐渐变差,塑性也逐渐减小,合金的屈服现象逐渐消失,合金的应变硬化现象逐渐减弱。除此之外,随着小角晶界取向差的增大,N5合金的持久性能降低,伸长率减小。

The second generation N5 single crystal superalloy was studied.The N5 alloy twin plates containing 5.4°,9.8°,15.8°and 18.4°low angle grain boundaries were prepared by seed crystal method using HRS technology.The standard samples prepared from N5 alloy twin plates with different low angle grain boundaries were tested for tensile properties at 870℃,transverse rupture properties at 750℃/820 MPa and 1093℃/158 MPa,and the fracture morphology was analyzed by means of scanning electron microscope.The results showed that with the increase of the orientation difference of low angle grain boundary,the tensile properties of the N5alloy gradually became worse,the plasticity gradually decreased,the yield phenomenon of the alloy gradually disappeared,and the strain hardening phenomenon of the alloy gradually weakened.In addition,with the increase of the low angle grain boundary orientation difference,the stress rupture property and elongation of the N5 alloy decreased.