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用双籽晶法制备了带有扭转小角度晶界的DD6单晶高温合金双晶试板。在760℃/758 MPa, 850℃/550 MPa 和 980℃/250 MPa条件下研究了小角度晶界对合金持久性能和断裂特征的影响,用扫描电镜分析了断口形貌和断裂机制。结果表明,晶界角度相对较小时,对合金的持久性能影响较小。在同一测试条件下,合金的持久性能随着晶界角度增大而减小。在同一测试条件下随着晶界角度增大,或者在相同晶界角度随着测试温度升高应力减小,持久断裂有逐渐出现沿晶断裂的趋势。
DD6 single crystal superalloy dual-crystal test plate with twisted small-angle grain boundaries was prepared by double-seed method. The effects of small-angle grain boundaries on the ductility and fracture properties of the alloys were investigated at 760 ℃ / 758 MPa, 850 ℃ / 550 MPa and 980 ℃ / 250 MPa. The fracture morphology and fracture mechanism were analyzed by SEM. The results show that when the grain boundary angle is relatively small, the lasting performance of the alloy is less affected. Under the same test conditions, the ductility of the alloy decreases as the grain boundary angle increases. Under the same test conditions, as the grain boundary angle increases, or the stress decreases with the increase of the test temperature at the same grain boundary, there is a tendency of gradual intergranular fracture in the permanent fracture.