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利用SEM和TEM,对固溶强化合金Hastelloy C-276的初始组织和在650℃、不同拉应力下持久断裂试样进行显微组织分析。结果表明:试样的断口以典型的韧窝形貌为主,局部有少许晶间断裂现象,显示出C-276合金具有良好的高温韧性。在C-276合金的初始组织中,有退火孪晶和大量位错存在;在经受高应力拉伸过程中,晶体内产生大量形变孪晶;同时,发现在晶界和晶内有细小弥散的析出物。因此,C-276合金在650℃下优越的高温持久抗力是固溶强化、沉淀强化以及可能的孪晶强化综合作用的结果。
SEM and TEM were used to analyze the microstructure of Hastelloy C-276 initial microstructure and the permanent tensile specimens under different tensile stress at 650 ℃. The results show that the fracture of the sample is dominated by the typical dimple morphology with a few intergranular fracture phenomena, indicating that the C-276 alloy has good high temperature toughness. In the initial microstructure of C-276 alloy, there are annealed twins and a large number of dislocations; a large amount of deformation twins are generated in the crystal during the high stress stretching; meanwhile, fine twists Precipitate. Therefore, the superior high-temperature long-term resistance of C-276 alloy at 650 ° C is the result of a combination of solution strengthening, precipitation strengthening and possible twinning.